Dataframe commands (#3498)

* Sample command

* Join command with checks

* More dataframes commands

* Groupby and aggregate commands

* Missing feature dataframe flag

* Renamed file

Cargo.lock

@@ -2843,6 +2843,12 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "libm"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7d73b3f436185384286bd8098d17ec07c9a7d2388a6599f824d8502b529702a"
+
 [[package]]
 name = "libnghttp2-sys"
 version = "0.1.6+1.43.0"
@@ -3760,9 +3766,6 @@ dependencies = [
  "polars",
  "serde 1.0.125",
  "serde_bytes",
- "serde_json",
- "serde_yaml",
- "toml",
 ]
 
 [[package]]
@@ -4253,6 +4256,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
 dependencies = [
  "autocfg",
+ "libm",
 ]
 
 [[package]]
@@ -4685,9 +4689,9 @@ dependencies = [
 
 [[package]]
 name = "polars"
-version = "0.13.3"
+version = "0.13.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bc4e2e025126632e8e19d53cd9b655da344bd4942ba603ad246c7776b6401844"
+checksum = "c406ce46726b7d33b05a343d9c1317c0803a419d50bb45275de3f366410e9a80"
 dependencies = [
  "polars-core",
  "polars-io",
@@ -4696,9 +4700,9 @@ dependencies = [
 
 [[package]]
 name = "polars-arrow"
-version = "0.13.3"
+version = "0.13.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3534c76a7bafaca9c783506a1f331ad746621d3808ab2407c02ffadd9e99326"
+checksum = "53b2d5fb400345c7977e4e728a10be382476f2f9d2caf6b57cd60e97ea17d364"
 dependencies = [
  "arrow",
  "num 0.4.0",
@@ -4707,9 +4711,9 @@ dependencies = [
 
 [[package]]
 name = "polars-core"
-version = "0.13.3"
+version = "0.13.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ad76c4d55017da2d0f8930b0caa327d12286c1e4407469f361e84fad176f9601"
+checksum = "88561e850748c507f0fc7835b35e795e770597ceecb14e0a8f7d8abf8346645d"
 dependencies = [
  "ahash 0.7.2",
  "anyhow",
@@ -4723,6 +4727,8 @@ dependencies = [
  "parquet",
  "polars-arrow",
  "prettytable-rs",
+ "rand 0.7.3",
+ "rand_distr",
  "rayon",
  "regex 1.5.3",
  "thiserror",
@@ -4731,9 +4737,9 @@ dependencies = [
 
 [[package]]
 name = "polars-io"
-version = "0.13.3"
+version = "0.13.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "07f20f27363d85f847a2b7e9d1bfd426bff18680691dd42ff17ca91893f12f89"
+checksum = "27388810ec5f3346838725aa0aa49343802c1344b96fe82229ae781c62c98bc7"
 dependencies = [
  "ahash 0.7.2",
  "anyhow",
@@ -4755,9 +4761,9 @@ dependencies = [
 
 [[package]]
 name = "polars-lazy"
-version = "0.13.3"
+version = "0.13.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "595906f951bacf223625ed6b0e4e73153eb9e251850bb2f9c36d78828334f32b"
+checksum = "0e7f83284970a9db7d0b6a56d6f944c3988587429c124c1d087188e9d2c7ad7c"
 dependencies = [
  "ahash 0.7.2",
  "itertools",
@@ -5089,6 +5095,16 @@ dependencies = [
  "getrandom 0.2.2",
 ]
 
+[[package]]
+name = "rand_distr"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c9e9532ada3929fb8b2e9dbe28d1e06c9b2cc65813f074fcb6bd5fbefeff9d56"
+dependencies = [
+ "num-traits 0.2.14",
+ "rand 0.7.3",
+]
+
 [[package]]
 name = "rand_hc"
 version = "0.2.0"

crates/nu-command/Cargo.toml

@@ -99,7 +99,10 @@ uuid_crate = { package = "uuid", version = "0.8.2", features = ["v4"], optional
 which = { version = "4.1.0", optional = true }
 zip = { version = "0.5.9", optional = true }
 
-polars = { version = "0.13.3",optional = true, features = ["parquet", "json"] }
+[dependencies.polars]
+version = "0.13.4"
+optional = true
+features = ["parquet", "json", "random"]
 
 [target.'cfg(unix)'.dependencies]
 umask = "1.0.0"

crates/nu-command/src/commands.rs

@@ -188,7 +188,11 @@ pub(crate) mod touch;
 pub(crate) use all::Command as All;
 pub(crate) use any::Command as Any;
 #[cfg(feature = "dataframe")]
-pub(crate) use dataframe::{DataFrame, DataFrameGroupBy, DataFrameList, DataFrameLoad};
+pub(crate) use dataframe::{
+    DataFrame, DataFrameAggregate, DataFrameConvert, DataFrameDTypes, DataFrameDrop,
+    DataFrameGroupBy, DataFrameJoin, DataFrameList, DataFrameLoad, DataFrameSample,
+    DataFrameSelect, DataFrameShow,
+};
 pub(crate) use enter::Enter;
 pub(crate) use every::Every;
 pub(crate) use exec::Exec;

crates/nu-command/src/commands/autoview/command.rs

@@ -8,6 +8,9 @@ use nu_protocol::hir::{self, Expression, ExternalRedirection, Literal, SpannedEx
 use nu_protocol::{Primitive, Signature, UntaggedValue, Value};
 use nu_table::TextStyle;
 
+#[cfg(feature = "dataframe")]
+use nu_protocol::dataframe::PolarsData;
+
 pub struct Command;
 
 impl WholeStreamCommand for Command {
@@ -236,8 +239,8 @@ pub fn autoview(args: CommandArgs) -> Result<OutputStream, ShellError> {
                     }
                     #[cfg(feature = "dataframe")]
                     Value {
-                        value: UntaggedValue::DataFrame(df),
+                        value: UntaggedValue::DataFrame(PolarsData::EagerDataFrame(df)),
-                        ..
+                        tag,
                     } => {
                         if let Some(table) = table {
                             // TODO. Configure the parameter rows from file. It can be
@@ -248,6 +251,20 @@ pub fn autoview(args: CommandArgs) -> Result<OutputStream, ShellError> {
                             let _ = result.collect::<Vec<_>>();
                         }
                     }
+                    #[cfg(feature = "dataframe")]
+                    Value {
+                        value: UntaggedValue::DataFrame(PolarsData::GroupBy(groupby)),
+                        tag,
+                    } => {
+                        if let Some(table) = table {
+                            // TODO. Configure the parameter rows from file. It can be
+                            // adjusted to see a certain amount of values in the head
+                            let command_args =
+                                create_default_command_args(&context, groupby.print()?.into(), tag);
+                            let result = table.run(command_args)?;
+                            let _ = result.collect::<Vec<_>>();
+                        }
+                    }
                     Value {
                         value: UntaggedValue::Primitive(Primitive::Nothing),
                         ..

crates/nu-command/src/commands/dataframe/aggregate.rs

@@ -0,0 +1,202 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, SyntaxShape, UntaggedValue, Value,
+};
+use nu_source::Tagged;
+use polars::frame::groupby::GroupBy;
+
+use super::utils::convert_columns;
+
+enum Operation {
+    Mean,
+    Sum,
+    Min,
+    Max,
+    First,
+    Last,
+    Nunique,
+    Quantile(f64),
+    Median,
+    Var,
+    Std,
+    Count,
+}
+
+impl Operation {
+    fn from_tagged(
+        name: &Tagged<String>,
+        quantile: Option<Tagged<f64>>,
+    ) -> Result<Operation, ShellError> {
+        match name.item.as_ref() {
+            "mean" => Ok(Operation::Mean),
+            "sum" => Ok(Operation::Sum),
+            "min" => Ok(Operation::Min),
+            "max" => Ok(Operation::Max),
+            "first" => Ok(Operation::First),
+            "last" => Ok(Operation::Last),
+            "nunique" => Ok(Operation::Nunique),
+            "quantile" => {
+                match quantile {
+                    None => Err(ShellError::labeled_error(
+                        "Quantile value not fount",
+                        "Quantile operation requires quantile value",
+                        &name.tag,
+                    )),
+                Some(value ) => {
+                    if (value.item < 0.0) | (value.item > 1.0) {
+                        Err(ShellError::labeled_error(
+                            "Inappropriate quantile",
+                            "Quantile value should be between 0.0 and 1.0",
+                            &value.tag,
+                        ))
+                    } else {
+                        Ok(Operation::Quantile(value.item))
+                    }
+                }
+                }
+            }
+            "median" => Ok(Operation::Median),
+            "var" => Ok(Operation::Var),
+            "std" => Ok(Operation::Std),
+            "count" => Ok(Operation::Count),
+            _ => Err(ShellError::labeled_error_with_secondary(
+                "Operation not fount",
+                "Operation does not exist",
+                &name.tag,
+                "Perhaps you want: mean, sum, min, max, first, last, nunique, quantile, median, count",
+                &name.tag,
+            )),
+        }
+    }
+}
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls aggregate"
+    }
+
+    fn usage(&self) -> &str {
+        "Performs an aggregation operation on a groupby object"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls aggregate")
+            .required("operation", SyntaxShape::String, "aggregate operation")
+            .optional(
+                "selection",
+                SyntaxShape::Table,
+                "columns to perform aggregation",
+            )
+            .named(
+                "quantile",
+                SyntaxShape::Number,
+                "quantile value for quantile operation",
+                Some('q'),
+            )
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        aggregate(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Aggregate sum by grouping by column a and summing on col b",
+            example:
+                "echo [[a b]; [one 1] [one 2]] | pls convert | pls groupby [a] | pls aggregate sum",
+            result: None,
+        }]
+    }
+}
+
+fn aggregate(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let mut args = args.evaluate_once()?;
+
+    let quantile: Option<Tagged<f64>> = args.get_flag("quantile")?;
+    let operation: Tagged<String> = args.req(0)?;
+    let op = Operation::from_tagged(&operation, quantile)?;
+
+    // Extracting the selection columns of the columns to perform the aggregation
+    let agg_cols: Option<Vec<Value>> = args.opt(1)?;
+    let (selection, agg_span) = match agg_cols {
+        Some(cols) => {
+            let (agg_string, agg_span) = convert_columns(&cols, &tag)?;
+            (Some(agg_string), agg_span)
+        }
+        None => (None, Span::unknown()),
+    };
+
+    // The operation is only done in one dataframe. Only one input is
+    // expected from the InputStream
+    match args.input.next() {
+        None => Err(ShellError::labeled_error(
+            "No input received",
+            "missing dataframe input from stream",
+            &tag,
+        )),
+        Some(value) => {
+            if let UntaggedValue::DataFrame(PolarsData::GroupBy(nu_groupby)) = value.value {
+                let groupby = nu_groupby.to_groupby()?;
+
+                let groupby = match &selection {
+                    Some(cols) => groupby.select(cols),
+                    None => groupby,
+                };
+
+                let res = perform_aggregation(groupby, op, &operation.tag, &agg_span)?;
+
+                let final_df = Value {
+                    tag,
+                    value: UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame::new(
+                        res,
+                    ))),
+                };
+
+                Ok(OutputStream::one(final_df))
+            } else {
+                Err(ShellError::labeled_error(
+                    "No groupby in stream",
+                    "no groupby found in input stream",
+                    &tag,
+                ))
+            }
+        }
+    }
+}
+
+fn perform_aggregation(
+    groupby: GroupBy,
+    operation: Operation,
+    operation_tag: &Tag,
+    agg_span: &Span,
+) -> Result<polars::prelude::DataFrame, ShellError> {
+    match operation {
+        Operation::Mean => groupby.mean(),
+        Operation::Sum => groupby.sum(),
+        Operation::Min => groupby.min(),
+        Operation::Max => groupby.max(),
+        Operation::First => groupby.first(),
+        Operation::Last => groupby.last(),
+        Operation::Nunique => groupby.n_unique(),
+        Operation::Quantile(quantile) => groupby.quantile(quantile),
+        Operation::Median => groupby.median(),
+        Operation::Var => groupby.var(),
+        Operation::Std => groupby.std(),
+        Operation::Count => groupby.count(),
+    }
+    .map_err(|e| {
+        let span = if e.to_string().contains("Not found") {
+            agg_span
+        } else {
+            &operation_tag.span
+        };
+
+        ShellError::labeled_error("Aggregation error", format!("{}", e), span)
+    })
+}

crates/nu-command/src/commands/dataframe/command.rs

@@ -1,38 +1,26 @@
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
-use nu_protocol::{dataframe::NuDataFrame, Signature, UntaggedValue};
+use nu_protocol::{Signature, UntaggedValue};
 
 pub struct Command;
 
 impl WholeStreamCommand for Command {
     fn name(&self) -> &str {
-        "dataframe"
+        "pls"
     }
 
     fn usage(&self) -> &str {
-        "Creates a dataframe from pipelined Table or List "
+        "Commands to work with polars dataframes"
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("dataframe")
+        Signature::build("pls")
     }
 
     fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
-        let tag = args.call_info.name_tag.clone();
+        Ok(OutputStream::one(
-        let args = args.evaluate_once()?;
+            UntaggedValue::string(get_full_help(&Command, args.scope())).into_value(Tag::unknown()),
-
+        ))
-        let df = NuDataFrame::try_from_iter(args.input, &tag)?;
-        let init = InputStream::one(UntaggedValue::DataFrame(df).into_value(&tag));
-
-        Ok(init.to_output_stream())
-    }
-
-    fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Takes an input stream and converts it to a dataframe",
-            example: "echo [[a b];[1 2] [3 4]] | dataframe",
-            result: None,
-        }]
     }
 }

crates/nu-command/src/commands/dataframe/convert.rs

@@ -0,0 +1,43 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, UntaggedValue,
+};
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls convert"
+    }
+
+    fn usage(&self) -> &str {
+        "Converts a pipelined Table or List into a polars dataframe"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls convert")
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        let tag = args.call_info.name_tag.clone();
+        let args = args.evaluate_once()?;
+
+        let df = NuDataFrame::try_from_iter(args.input, &tag)?;
+        let init = InputStream::one(
+            UntaggedValue::DataFrame(PolarsData::EagerDataFrame(df)).into_value(&tag),
+        );
+
+        Ok(init.to_output_stream())
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Takes an input stream and converts it to a polars dataframe",
+            example: "echo [[a b];[1 2] [3 4]] | pls convert",
+            result: None,
+        }]
+    }
+}

crates/nu-command/src/commands/dataframe/drop.rs

@@ -0,0 +1,97 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, SyntaxShape, UntaggedValue, Value,
+};
+
+use super::utils::convert_columns;
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls drop"
+    }
+
+    fn usage(&self) -> &str {
+        "Creates a new dataframe by dropping the selected columns"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls drop").required(
+            "columns",
+            SyntaxShape::Table,
+            "column names to be dropped",
+        )
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        drop(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "drop column a",
+            example: "echo [[a b]; [1 2] [3 4]] | pls convert | pls drop [a]",
+            result: None,
+        }]
+    }
+}
+
+fn drop(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let mut args = args.evaluate_once()?;
+
+    let columns: Vec<Value> = args.req(0)?;
+
+    let (col_string, col_span) = convert_columns(&columns, &tag)?;
+
+    match args.input.next() {
+        None => Err(ShellError::labeled_error(
+            "No input received",
+            "missing dataframe input from stream",
+            &tag,
+        )),
+        Some(value) => {
+            if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame {
+                dataframe: Some(ref df),
+                ..
+            })) = value.value
+            {
+                let new_df = match col_string.iter().next() {
+                    Some(col) => df.drop(col).map_err(|e| {
+                        ShellError::labeled_error("Join error", format!("{}", e), &col_span)
+                    }),
+                    None => Err(ShellError::labeled_error(
+                        "Empty names list",
+                        "No column names where found",
+                        &col_span,
+                    )),
+                }?;
+
+                let res = col_string.iter().skip(1).try_fold(new_df, |new_df, col| {
+                    new_df.drop(col).map_err(|e| {
+                        ShellError::labeled_error("Drop error", format!("{}", e), &col_span)
+                    })
+                })?;
+
+                let value = Value {
+                    value: UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame::new(
+                        res,
+                    ))),
+                    tag: tag.clone(),
+                };
+
+                Ok(OutputStream::one(value))
+            } else {
+                Err(ShellError::labeled_error(
+                    "No dataframe in stream",
+                    "no dataframe found in input stream",
+                    &tag,
+                ))
+            }
+        }
+    }
+}

crates/nu-command/src/commands/dataframe/dtypes.rs

@@ -0,0 +1,81 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, TaggedDictBuilder, UntaggedValue,
+};
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls dtypes"
+    }
+
+    fn usage(&self) -> &str {
+        "Show dataframe data types"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls dtypes")
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        dtypes(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "drop column a",
+            example: "echo [[a b]; [1 2] [3 4]] | pls convert | pls dtypes",
+            result: None,
+        }]
+    }
+}
+
+fn dtypes(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let mut args = args.evaluate_once()?;
+
+    match args.input.next() {
+        None => Err(ShellError::labeled_error(
+            "No input received",
+            "missing dataframe input from stream",
+            &tag,
+        )),
+        Some(value) => {
+            if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame {
+                dataframe: Some(df),
+                ..
+            })) = value.value
+            {
+                let col_names = df
+                    .get_column_names()
+                    .iter()
+                    .map(|v| v.to_string())
+                    .collect::<Vec<String>>();
+
+                let values =
+                    df.dtypes()
+                        .into_iter()
+                        .zip(col_names.into_iter())
+                        .map(move |(dtype, name)| {
+                            let mut data = TaggedDictBuilder::new(tag.clone());
+                            data.insert_value("column", name.as_ref());
+                            data.insert_value("dtype", format!("{}", dtype));
+
+                            data.into_value()
+                        });
+
+                Ok(OutputStream::from_stream(values))
+            } else {
+                Err(ShellError::labeled_error(
+                    "No dataframe in stream",
+                    "no dataframe found in input stream",
+                    &tag,
+                ))
+            }
+        }
+    }
+}

crates/nu-command/src/commands/dataframe/groupby.rs

@@ -2,99 +2,28 @@ use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
 use nu_protocol::{
-    dataframe::NuDataFrame, Primitive, Signature, SyntaxShape, UntaggedValue, Value,
+    dataframe::{NuDataFrame, NuGroupBy, PolarsData},
+    Signature, SyntaxShape, UntaggedValue, Value,
 };
-use nu_source::Tagged;
-use polars::frame::groupby::GroupBy;
 
-enum Operation {
+use super::utils::convert_columns;
-    Mean,
-    Sum,
-    Min,
-    Max,
-    First,
-    Last,
-    Nunique,
-    Quantile(f64),
-    Median,
-    //Var,
-    //Std,
-    Count,
-}
-
-impl Operation {
-    fn from_tagged(
-        name: &Tagged<String>,
-        quantile: Option<Tagged<f64>>,
-    ) -> Result<Operation, ShellError> {
-        match name.item.as_ref() {
-            "mean" => Ok(Operation::Mean),
-            "sum" => Ok(Operation::Sum),
-            "min" => Ok(Operation::Min),
-            "max" => Ok(Operation::Max),
-            "first" => Ok(Operation::First),
-            "last" => Ok(Operation::Last),
-            "nunique" => Ok(Operation::Nunique),
-            "quantile" => {
-                match quantile {
-                    None => Err(ShellError::labeled_error(
-                        "Quantile value not fount",
-                        "Quantile operation requires quantile value",
-                        &name.tag,
-                    )),
-                Some(value ) => {
-                    if (value.item < 0.0) | (value.item > 1.0) {
-                        Err(ShellError::labeled_error(
-                            "Inappropriate quantile",
-                            "Quantile value should be between 0.0 and 1.0",
-                            &value.tag,
-                        ))
-                    } else {
-                        Ok(Operation::Quantile(value.item))
-                    }
-                }
-                }
-            }
-            "median" => Ok(Operation::Median),
-            //"var" => Ok(Operation::Var),
-            //"std" => Ok(Operation::Std),
-            "count" => Ok(Operation::Count),
-            _ => Err(ShellError::labeled_error_with_secondary(
-                "Operation not fount",
-                "Operation does not exist",
-                &name.tag,
-                "Perhaps you want: mean, sum, min, max, first, last, nunique, quantile, median, count",
-                &name.tag,
-            )),
-        }
-    }
-}
 
 pub struct DataFrame;
 
 impl WholeStreamCommand for DataFrame {
     fn name(&self) -> &str {
-        "dataframe groupby"
+        "pls groupby"
     }
 
     fn usage(&self) -> &str {
-        "Creates a groupby operation on a dataframe"
+        "Creates a groupby object that can be used for other aggregations"
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("dataframe groupby")
+        Signature::build("pls groupby").required(
-            .required("columns", SyntaxShape::Table, "groupby columns")
+            "by columns",
-            .required(
-                "aggregation columns",
             SyntaxShape::Table,
-                "columns to perform aggregation",
+            "groupby columns",
-            )
-            .required("operation", SyntaxShape::String, "aggregate operation")
-            .named(
-                "quantile",
-                SyntaxShape::Number,
-                "auantile value for quantile operation",
-                Some('q'),
         )
     }
 
@@ -104,8 +33,8 @@ impl WholeStreamCommand for DataFrame {
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
-            description: "",
+            description: "Grouping by column a",
-            example: "",
+            example: "echo [[a b]; [one 1] [one 2]] | pls convert | pls groupby [a]",
             result: None,
         }]
     }
@@ -115,77 +44,9 @@ fn groupby(args: CommandArgs) -> Result<OutputStream, ShellError> {
     let tag = args.call_info.name_tag.clone();
     let mut args = args.evaluate_once()?;
 
-    let quantile: Option<Tagged<f64>> = args.get_flag("quantile")?;
-    let operation: Tagged<String> = args.req(2)?;
-    let op = Operation::from_tagged(&operation, quantile)?;
-
     // Extracting the names of the columns to perform the groupby
-    let columns: Vec<Value> = args.req(0)?;
+    let by_columns: Vec<Value> = args.req(0)?;
-
+    let (columns_string, col_span) = convert_columns(&by_columns, &tag)?;
-    // Extracting the first tag from the groupby column names
-    let mut col_span = match columns
-        .iter()
-        .nth(0)
-        .map(|v| Span::new(v.tag.span.start(), v.tag.span.end()))
-    {
-        Some(span) => span,
-        None => {
-            return Err(ShellError::labeled_error(
-                "Empty groupby names list",
-                "Empty list for groupby column names",
-                &tag,
-            ))
-        }
-    };
-
-    let columns_string = columns
-        .into_iter()
-        .map(|value| match value.value {
-            UntaggedValue::Primitive(Primitive::String(s)) => {
-                col_span = col_span.until(value.tag.span);
-                Ok(s)
-            }
-            _ => Err(ShellError::labeled_error(
-                "Incorrect column format",
-                "Only string as column name",
-                &value.tag,
-            )),
-        })
-        .collect::<Result<Vec<String>, _>>()?;
-
-    // Extracting the names of the columns to perform the aggregation
-    let agg_cols: Vec<Value> = args.req(1)?;
-
-    // Extracting the first tag from the aggregation column names
-    let mut agg_span = match agg_cols
-        .iter()
-        .nth(0)
-        .map(|v| Span::new(v.tag.span.start(), v.tag.span.end()))
-    {
-        Some(span) => span,
-        None => {
-            return Err(ShellError::labeled_error(
-                "Empty aggregation names list",
-                "Empty list for aggregation column names",
-                &tag,
-            ))
-        }
-    };
-
-    let aggregation_string = agg_cols
-        .into_iter()
-        .map(|value| match value.value {
-            UntaggedValue::Primitive(Primitive::String(s)) => {
-                agg_span = agg_span.until(value.tag.span);
-                Ok(s)
-            }
-            _ => Err(ShellError::labeled_error(
-                "Incorrect column format",
-                "Only string as column name",
-                value.tag,
-            )),
-        })
-        .collect::<Result<Vec<String>, _>>()?;
 
     // The operation is only done in one dataframe. Only one input is
     // expected from the InputStream
@@ -196,29 +57,31 @@ fn groupby(args: CommandArgs) -> Result<OutputStream, ShellError> {
             &tag,
         )),
         Some(value) => {
-            if let UntaggedValue::DataFrame(NuDataFrame {
+            if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(nu_df)) = value.value {
-                dataframe: Some(df),
+                let df = match nu_df.dataframe {
-                ..
+                    Some(df) => df,
-            }) = value.value
+                    None => unreachable!("No dataframe in nu_dataframe"),
-            {
-                let groupby = df
-                    .groupby(&columns_string)
-                    .map_err(|e| {
-                        ShellError::labeled_error("Groupby error", format!("{}", e), col_span)
-                    })?
-                    .select(&aggregation_string);
-
-                let res = perform_aggregation(groupby, op, &operation.tag, &agg_span)?;
-
-                let final_df = Value {
-                    tag,
-                    value: UntaggedValue::DataFrame(NuDataFrame {
-                        dataframe: Some(res),
-                        name: "agg result".to_string(),
-                    }),
                 };
 
-                Ok(OutputStream::one(final_df))
+                // This is the expensive part of the groupby; to create the
+                // groups that will be used for grouping the data in the
+                // dataframe. Once it has been done these values can be stored
+                // in the NuGroupBy
+                let groupby = df.groupby(&columns_string).map_err(|e| {
+                    ShellError::labeled_error("Groupby error", format!("{}", e), col_span)
+                })?;
+
+                let groups = groupby.get_groups().to_vec();
+                let groupby = Value {
+                    tag: value.tag,
+                    value: UntaggedValue::DataFrame(PolarsData::GroupBy(NuGroupBy::new(
+                        NuDataFrame::new_with_name(df, nu_df.name),
+                        columns_string,
+                        groups,
+                    ))),
+                };
+
+                Ok(OutputStream::one(groupby))
             } else {
                 Err(ShellError::labeled_error(
                     "No dataframe in stream",
@@ -229,34 +92,3 @@ fn groupby(args: CommandArgs) -> Result<OutputStream, ShellError> {
         }
     }
 }
-
-fn perform_aggregation(
-    groupby: GroupBy,
-    operation: Operation,
-    operation_tag: &Tag,
-    agg_span: &Span,
-) -> Result<polars::prelude::DataFrame, ShellError> {
-    match operation {
-        Operation::Mean => groupby.mean(),
-        Operation::Sum => groupby.sum(),
-        Operation::Min => groupby.min(),
-        Operation::Max => groupby.max(),
-        Operation::First => groupby.first(),
-        Operation::Last => groupby.last(),
-        Operation::Nunique => groupby.n_unique(),
-        Operation::Quantile(quantile) => groupby.quantile(quantile),
-        Operation::Median => groupby.median(),
-        //Operation::Var => groupby.var(),
-        //Operation::Std => groupby.std(),
-        Operation::Count => groupby.count(),
-    }
-    .map_err(|e| {
-        let span = if e.to_string().contains("Not found") {
-            agg_span
-        } else {
-            &operation_tag.span
-        };
-
-        ShellError::labeled_error("Aggregation error", format!("{}", e), span)
-    })
-}

crates/nu-command/src/commands/dataframe/join.rs

@@ -0,0 +1,205 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, SyntaxShape, UntaggedValue, Value,
+};
+
+use super::utils::convert_columns;
+
+use polars::prelude::JoinType;
+
+use nu_source::Tagged;
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls join"
+    }
+
+    fn usage(&self) -> &str {
+        "Joins a dataframe using columns as reference"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls join")
+            .required("dataframe", SyntaxShape::Any, "right dataframe to join")
+            .required(
+                "l_columns",
+                SyntaxShape::Table,
+                "left column names to perform join",
+            )
+            .required(
+                "r_columns",
+                SyntaxShape::Table,
+                "right column names to perform join",
+            )
+            .named(
+                "type",
+                SyntaxShape::String,
+                "type of join. Inner by default",
+                Some('t'),
+            )
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        join(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "inner join dataframe",
+                example: "echo [[a b]; [1 2] [3 4]] | pls convert | pls join $right [a] [a]",
+                result: None,
+            },
+            Example {
+                description: "right join dataframe",
+                example:
+                    "echo [[a b]; [1 2] [3 4] [5 6]] | pls convert | pls join $right [b] [b] -t right",
+                result: None,
+            },
+        ]
+    }
+}
+
+fn join(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let mut args = args.evaluate_once()?;
+
+    let r_df: Value = args.req(0)?;
+    let l_col: Vec<Value> = args.req(1)?;
+    let r_col: Vec<Value> = args.req(2)?;
+    let join_type_op: Option<Tagged<String>> = args.get_flag("type")?;
+
+    let join_type = match join_type_op {
+        None => JoinType::Inner,
+        Some(val) => match val.item.as_ref() {
+            "inner" => JoinType::Inner,
+            "outer" => JoinType::Outer,
+            "left" => JoinType::Left,
+            _ => {
+                return Err(ShellError::labeled_error_with_secondary(
+                    "Incorrect join type",
+                    "Invalid join type",
+                    &val.tag,
+                    "Perhaps you mean: inner, outer or left",
+                    &val.tag,
+                ))
+            }
+        },
+    };
+
+    let (l_col_string, l_col_span) = convert_columns(&l_col, &tag)?;
+    let (r_col_string, r_col_span) = convert_columns(&r_col, &tag)?;
+
+    match args.input.next() {
+        None => Err(ShellError::labeled_error(
+            "No input received",
+            "missing dataframe input from stream",
+            &tag,
+        )),
+        Some(value) => {
+            if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame {
+                dataframe: Some(ref df),
+                ..
+            })) = value.value
+            {
+                let res = match r_df.value {
+                    UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame {
+                        dataframe: Some(r_df),
+                        ..
+                    })) => {
+                        // Checking the column types before performing the join
+                        check_column_datatypes(
+                            df,
+                            &l_col_string,
+                            &l_col_span,
+                            &r_col_string,
+                            &r_col_span,
+                        )?;
+
+                        df.join(&r_df, &l_col_string, &r_col_string, join_type)
+                            .map_err(|e| {
+                                ShellError::labeled_error(
+                                    "Join error",
+                                    format!("{}", e),
+                                    &l_col_span,
+                                )
+                            })
+                    }
+                    _ => Err(ShellError::labeled_error(
+                        "Not a dataframe",
+                        "not a dataframe type value",
+                        &r_df.tag,
+                    )),
+                }?;
+
+                let value = Value {
+                    value: UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame::new(
+                        res,
+                    ))),
+                    tag: tag.clone(),
+                };
+
+                Ok(OutputStream::one(value))
+            } else {
+                Err(ShellError::labeled_error(
+                    "No dataframe in stream",
+                    "no dataframe found in input stream",
+                    &tag,
+                ))
+            }
+        }
+    }
+}
+
+fn check_column_datatypes<T: AsRef<str>>(
+    df: &polars::prelude::DataFrame,
+    l_cols: &[T],
+    l_col_span: &Span,
+    r_cols: &[T],
+    r_col_span: &Span,
+) -> Result<(), ShellError> {
+    if l_cols.len() != r_cols.len() {
+        return Err(ShellError::labeled_error_with_secondary(
+            "Mismatched number of column names",
+            format!(
+                "found {} left names vs {} right names",
+                l_cols.len(),
+                r_cols.len()
+            ),
+            l_col_span,
+            "perhaps you need to change the number of columns to join",
+            r_col_span,
+        ));
+    }
+
+    for (l, r) in l_cols.iter().zip(r_cols.iter()) {
+        let l_series = df
+            .column(l.as_ref())
+            .map_err(|e| ShellError::labeled_error("Join error", format!("{}", e), l_col_span))?;
+
+        let r_series = df
+            .column(r.as_ref())
+            .map_err(|e| ShellError::labeled_error("Join error", format!("{}", e), r_col_span))?;
+
+        if l_series.dtype() != r_series.dtype() {
+            return Err(ShellError::labeled_error_with_secondary(
+                "Mismatched datatypes",
+                format!(
+                    "left column type '{}' doesn't match '{}' right column match",
+                    l_series.dtype(),
+                    r_series.dtype()
+                ),
+                l_col_span,
+                "perhaps you need to select other column to match",
+                r_col_span,
+            ));
+        }
+    }
+
+    Ok(())
+}

crates/nu-command/src/commands/dataframe/list.rs

@@ -1,13 +1,16 @@
 use crate::prelude::*;
 use nu_engine::WholeStreamCommand;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, TaggedDictBuilder, UntaggedValue,
+};
 
 pub struct DataFrame;
 
 impl WholeStreamCommand for DataFrame {
     fn name(&self) -> &str {
-        "dataframe list"
+        "pls list"
     }
 
     fn usage(&self) -> &str {
@@ -15,38 +18,46 @@ impl WholeStreamCommand for DataFrame {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("dataframe list")
+        Signature::build("pls list")
     }
 
     fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
         let args = args.evaluate_once()?;
 
-        let mut dataframes: Vec<Value> = Vec::new();
+        let values = args
-        for (name, value) in args.context.scope.get_vars() {
+            .context
-            if let UntaggedValue::DataFrame(df) = value.value {
+            .scope
-                let mut data = TaggedDictBuilder::new(value.tag);
+            .get_vars()
+            .into_iter()
+            .filter_map(|(name, value)| {
+                if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame {
+                    dataframe: Some(df),
+                    name: file_name,
+                })) = &value.value
+                {
+                    let mut data = TaggedDictBuilder::new(value.tag.clone());
 
-                let polars_df = df.dataframe.unwrap();
+                    let rows = df.height();
+                    let cols = df.width();
 
-                let rows = polars_df.height();
+                    data.insert_value("name", name.as_ref());
-                let cols = polars_df.width();
+                    data.insert_value("file", file_name.as_ref());
-
-                data.insert_value("name", name);
-                data.insert_value("file", df.name);
                     data.insert_value("rows", format!("{}", rows));
                     data.insert_value("columns", format!("{}", cols));
 
-                dataframes.push(data.into_value());
+                    Some(data.into_value())
-            }
+                } else {
+                    None
                 }
+            });
 
-        Ok(OutputStream::from_stream(dataframes.into_iter()))
+        Ok(OutputStream::from_stream(values))
     }
 
     fn examples(&self) -> Vec<Example> {
         vec![Example {
             description: "Lists loaded dataframes in current scope",
-            example: "dataframe list",
+            example: "pls list",
             result: None,
         }]
     }

crates/nu-command/src/commands/dataframe/load.rs

@@ -4,7 +4,8 @@ use crate::prelude::*;
 use nu_engine::{EvaluatedCommandArgs, WholeStreamCommand};
 use nu_errors::ShellError;
 use nu_protocol::{
-    dataframe::NuDataFrame, Primitive, Signature, SyntaxShape, UntaggedValue, Value,
+    dataframe::{NuDataFrame, PolarsData},
+    Primitive, Signature, SyntaxShape, UntaggedValue, Value,
 };
 
 use nu_source::Tagged;
@@ -15,7 +16,7 @@ pub struct DataFrame;
 
 impl WholeStreamCommand for DataFrame {
     fn name(&self) -> &str {
-        "dataframe load"
+        "pls load"
     }
 
     fn usage(&self) -> &str {
@@ -23,7 +24,7 @@ impl WholeStreamCommand for DataFrame {
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("dataframe load")
+        Signature::build("pls load")
             .required(
                 "file",
                 SyntaxShape::FilePath,
@@ -67,7 +68,7 @@ impl WholeStreamCommand for DataFrame {
     fn examples(&self) -> Vec<Example> {
         vec![Example {
             description: "Takes a file name and creates a dataframe",
-            example: "dataframe load test.csv",
+            example: "pls load test.csv",
             result: None,
         }]
     }
@@ -85,7 +86,7 @@ fn create_from_file(args: CommandArgs) -> Result<OutputStream, ShellError> {
             Some("json") => from_json(args),
             _ => Err(ShellError::labeled_error(
                 "Error with file",
-                "Not a csv or parquet file",
+                "Not a csv, parquet or json file",
                 &file.tag,
             )),
         },
@@ -107,12 +108,12 @@ fn create_from_file(args: CommandArgs) -> Result<OutputStream, ShellError> {
         }
     };
 
-    let nu_dataframe = NuDataFrame {
+    let init = InputStream::one(
-        dataframe: Some(df),
+        UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame::new_with_name(
-        name: file_name,
+            df, file_name,
-    };
+        )))
-
+        .into_value(&tag),
-    let init = InputStream::one(UntaggedValue::DataFrame(nu_dataframe).into_value(&tag));
+    );
 
     Ok(init.to_output_stream())
 }

crates/nu-command/src/commands/dataframe/mod.rs

@@ -1,9 +1,26 @@
+pub mod aggregate;
 pub mod command;
+pub mod convert;
+pub mod drop;
+pub mod dtypes;
 pub mod groupby;
+pub mod join;
 pub mod list;
 pub mod load;
+pub mod sample;
+pub mod select;
+pub mod show;
+pub(crate) mod utils;
 
+pub use aggregate::DataFrame as DataFrameAggregate;
 pub use command::Command as DataFrame;
+pub use convert::DataFrame as DataFrameConvert;
+pub use drop::DataFrame as DataFrameDrop;
+pub use dtypes::DataFrame as DataFrameDTypes;
 pub use groupby::DataFrame as DataFrameGroupBy;
+pub use join::DataFrame as DataFrameJoin;
 pub use list::DataFrame as DataFrameList;
 pub use load::DataFrame as DataFrameLoad;
+pub use sample::DataFrame as DataFrameSample;
+pub use select::DataFrame as DataFrameSelect;
+pub use show::DataFrame as DataFrameShow;

crates/nu-command/src/commands/dataframe/sample.rs

@@ -0,0 +1,117 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, SyntaxShape, UntaggedValue, Value,
+};
+
+use nu_source::Tagged;
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls sample"
+    }
+
+    fn usage(&self) -> &str {
+        "Create sample dataframe"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls load")
+            .named(
+                "n_rows",
+                SyntaxShape::Number,
+                "number of rows to be taken from dataframe",
+                Some('n'),
+            )
+            .named(
+                "fraction",
+                SyntaxShape::Number,
+                "fraction of dataframe to be taken",
+                Some('f'),
+            )
+            .switch("replace", "sample with replace", Some('e'))
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        sample(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Sample rows from dataframe",
+                example: "echo [[a b]; [1 2] [3 4]] | pls load | pls sample -r 1",
+                result: None,
+            },
+            Example {
+                description: "Shows sample row using fraction and replace",
+                example: "echo [[a b]; [1 2] [3 4] [5 6]] | pls load | pls sample -f 0.5 -e",
+                result: None,
+            },
+        ]
+    }
+}
+
+fn sample(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let mut args = args.evaluate_once()?;
+
+    let rows: Option<Tagged<usize>> = args.get_flag("n_rows")?;
+    let fraction: Option<Tagged<f64>> = args.get_flag("fraction")?;
+    let replace: bool = args.has_flag("replace");
+
+    match args.input.next() {
+        None => Err(ShellError::labeled_error(
+            "No input received",
+            "missing dataframe input from stream",
+            &tag,
+        )),
+        Some(value) => {
+            if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame {
+                dataframe: Some(ref df),
+                ..
+            })) = value.value
+            {
+                let res = match (rows, fraction) {
+                    (Some(rows), None) => df.sample_n(rows.item, replace).map_err(|e| {
+                        ShellError::labeled_error("Polars error", format!("{}", e), &rows.tag)
+                    }),
+                    (None, Some(frac)) => df.sample_frac(frac.item, replace).map_err(|e| {
+                        ShellError::labeled_error("Polars error", format!("{}", e), &frac.tag)
+                    }),
+                    (Some(_), Some(_)) => Err(ShellError::labeled_error(
+                        "Incompatible flags",
+                        "Only one selection criterion allowed",
+                        &tag,
+                    )),
+                    (None, None) => Err(ShellError::labeled_error_with_secondary(
+                        "No selection",
+                        "No selection criterion was found",
+                        &tag,
+                        "Perhaps you want to use the flag -n or -f",
+                        &tag,
+                    )),
+                }?;
+
+                let value = Value {
+                    value: UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame::new(
+                        res,
+                    ))),
+                    tag: tag.clone(),
+                };
+
+                Ok(OutputStream::one(value))
+            } else {
+                Err(ShellError::labeled_error(
+                    "No dataframe in stream",
+                    "no dataframe found in input stream",
+                    &tag,
+                ))
+            }
+        }
+    }
+}

crates/nu-command/src/commands/dataframe/select.rs

@@ -0,0 +1,84 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{NuDataFrame, PolarsData},
+    Signature, SyntaxShape, UntaggedValue, Value,
+};
+
+use super::utils::convert_columns;
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls select"
+    }
+
+    fn usage(&self) -> &str {
+        "Creates a new dataframe with the selected columns"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls select").required(
+            "columns",
+            SyntaxShape::Table,
+            "selected column names",
+        )
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        select(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Create new dataframe with column a",
+            example: "echo [[a b]; [1 2] [3 4]] | pls convert | pls select [a]",
+            result: None,
+        }]
+    }
+}
+
+fn select(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let mut args = args.evaluate_once()?;
+
+    let columns: Vec<Value> = args.req(0)?;
+
+    let (col_string, col_span) = convert_columns(&columns, &tag)?;
+
+    match args.input.next() {
+        None => Err(ShellError::labeled_error(
+            "No input received",
+            "missing dataframe input from stream",
+            &tag,
+        )),
+        Some(value) => {
+            if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame {
+                dataframe: Some(ref df),
+                ..
+            })) = value.value
+            {
+                let res = df.select(&col_string).map_err(|e| {
+                    ShellError::labeled_error("Drop error", format!("{}", e), &col_span)
+                })?;
+
+                let value = Value {
+                    value: UntaggedValue::DataFrame(PolarsData::EagerDataFrame(NuDataFrame::new(
+                        res,
+                    ))),
+                    tag: tag.clone(),
+                };
+
+                Ok(OutputStream::one(value))
+            } else {
+                Err(ShellError::labeled_error(
+                    "No dataframe in stream",
+                    "no dataframe found in input stream",
+                    &tag,
+                ))
+            }
+        }
+    }
+}

crates/nu-command/src/commands/dataframe/show.rs

@@ -0,0 +1,78 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{dataframe::PolarsData, Signature, SyntaxShape, UntaggedValue};
+
+use nu_source::Tagged;
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "pls show"
+    }
+
+    fn usage(&self) -> &str {
+        "Show dataframe"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("pls show")
+            .named(
+                "n_rows",
+                SyntaxShape::Number,
+                "number of rows to be shown",
+                Some('n'),
+            )
+            .switch("tail", "shows tail rows", Some('t'))
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        show(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Shows head rows from dataframe",
+                example: "echo [[a b]; [1 2] [3 4]] | pls convert | pls show",
+                result: None,
+            },
+            Example {
+                description: "Shows tail rows from dataframe",
+                example: "echo [[a b]; [1 2] [3 4] [5 6]] | pls convert | pls show -t -n 1",
+                result: None,
+            },
+        ]
+    }
+}
+
+fn show(args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let mut args = args.evaluate_once()?;
+
+    let rows: Option<Tagged<usize>> = args.get_flag("rows")?;
+    let tail: bool = args.has_flag("tail");
+
+    match args.input.next() {
+        None => Err(ShellError::labeled_error(
+            "No input received",
+            "missing dataframe input from stream",
+            &tag,
+        )),
+        Some(value) => {
+            if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(df)) = value.value {
+                let rows = rows.map(|v| v.item);
+                let values = if tail { df.tail(rows)? } else { df.head(rows)? };
+
+                Ok(OutputStream::from_stream(values.into_iter()))
+            } else {
+                Err(ShellError::labeled_error(
+                    "No dataframe in stream",
+                    "no dataframe found in input stream",
+                    &tag,
+                ))
+            }
+        }
+    }
+}

crates/nu-command/src/commands/dataframe/utils.rs

@@ -0,0 +1,42 @@
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{Primitive, UntaggedValue, Value};
+
+// Converts a Vec<Value> to a Vec<String> with a Span marking the whole
+// location of the columns for error referencing
+pub(crate) fn convert_columns<'columns>(
+    columns: &'columns [Value],
+    tag: &Tag,
+) -> Result<(Vec<String>, Span), ShellError> {
+    let mut col_span = match columns
+        .iter()
+        .nth(0)
+        .map(|v| Span::new(v.tag.span.start(), v.tag.span.end()))
+    {
+        Some(span) => span,
+        None => {
+            return Err(ShellError::labeled_error(
+                "Empty column list",
+                "Empty list found for command",
+                tag,
+            ))
+        }
+    };
+
+    let res = columns
+        .iter()
+        .map(|value| match &value.value {
+            UntaggedValue::Primitive(Primitive::String(s)) => {
+                col_span = col_span.until(value.tag.span);
+                Ok(s.clone())
+            }
+            _ => Err(ShellError::labeled_error(
+                "Incorrect column format",
+                "Only string as column name",
+                &value.tag,
+            )),
+        })
+        .collect::<Result<Vec<String>, _>>()?;
+
+    Ok((res, col_span))
+}

crates/nu-command/src/commands/default_context.rs

@@ -253,14 +253,31 @@ pub fn create_default_context(interactive: bool) -> Result<EvaluationContext, Bo
             whole_stream_command(Seq),
             whole_stream_command(SeqDates),
             whole_stream_command(TermSize),
+            //Dataframe commands
             #[cfg(feature = "dataframe")]
             whole_stream_command(DataFrame),
             #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameConvert),
+            #[cfg(feature = "dataframe")]
             whole_stream_command(DataFrameLoad),
             #[cfg(feature = "dataframe")]
             whole_stream_command(DataFrameList),
             #[cfg(feature = "dataframe")]
             whole_stream_command(DataFrameGroupBy),
+            #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameAggregate),
+            #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameShow),
+            #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameSample),
+            #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameJoin),
+            #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameDrop),
+            #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameSelect),
+            #[cfg(feature = "dataframe")]
+            whole_stream_command(DataFrameDTypes),
         ]);
 
         #[cfg(feature = "clipboard-cli")]

crates/nu-data/src/config.rs

@@ -117,7 +117,7 @@ fn helper(v: &Value) -> Result<toml::Value, ShellError> {
         UntaggedValue::Error(e) => return Err(e.clone()),
         UntaggedValue::Block(_) => toml::Value::String("<Block>".to_string()),
         #[cfg(feature = "dataframe")]
-        UntaggedValue::DataFrame(_) => toml::Value::String("<Data>".to_string()),
+        UntaggedValue::DataFrame(_) => toml::Value::String("<DataFrame>".to_string()),
         UntaggedValue::Primitive(Primitive::Range(_)) => toml::Value::String("<Range>".to_string()),
         UntaggedValue::Primitive(Primitive::Binary(b)) => {
             toml::Value::Array(b.iter().map(|x| toml::Value::Integer(*x as i64)).collect())

crates/nu-protocol/Cargo.toml

@@ -25,7 +25,9 @@ num-traits = "0.2.14"
 serde = { version = "1.0", features = ["derive"] }
 serde_bytes = "0.11.5"
 
-polars = {version="0.13.3", optional = true}
+[dependencies.polars]
+version = "0.13.4"
+optional = true
 
 # implement conversions
 serde_json = "1.0"

crates/nu-protocol/src/dataframe/mod.rs

@@ -1,3 +1,12 @@
 pub mod nu_dataframe;
+pub mod nu_groupby;
 
 pub use nu_dataframe::NuDataFrame;
+pub use nu_groupby::NuGroupBy;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Serialize, Deserialize)]
+pub enum PolarsData {
+    EagerDataFrame(NuDataFrame),
+    GroupBy(NuGroupBy),
+}

crates/nu-protocol/src/dataframe/nu_dataframe.rs

@@ -59,8 +59,18 @@ impl Default for NuDataFrame {
 }
 
 impl NuDataFrame {
-    fn new() -> Self {
+    pub fn new(df: polars::prelude::DataFrame) -> Self {
-        Self::default()
+        NuDataFrame {
+            dataframe: Some(df),
+            name: String::from("dataframe"),
+        }
+    }
+
+    pub fn new_with_name(df: polars::prelude::DataFrame, name: String) -> Self {
+        NuDataFrame {
+            dataframe: Some(df),
+            name,
+        }
     }
 }
 
@@ -103,7 +113,7 @@ impl<'de> Deserialize<'de> for NuDataFrame {
     where
         D: Deserializer<'de>,
     {
-        deserializer.deserialize_i32(NuDataFrame::new())
+        deserializer.deserialize_i32(NuDataFrame::default())
     }
 }
 
@@ -137,22 +147,23 @@ impl NuDataFrame {
     // Print is made out a head and if the dataframe is too large, then a tail
     pub fn print(&self) -> Result<Vec<Value>, ShellError> {
         if let Some(df) = &self.dataframe {
-            let size: usize = 5;
+            let size: usize = 20;
-            let mut values = self.head(Some(size))?;
 
             if df.height() > size {
+                let sample_size = size / 2;
+                let mut values = self.head(Some(sample_size))?;
                 add_separator(&mut values, df);
-
+                let remaining = df.height() - sample_size;
-                let remaining = df.height() - size;
+                let tail_size = remaining.min(sample_size);
-                let tail_size = remaining.min(size);
                 let mut tail_values = self.tail(Some(tail_size))?;
-
                 values.append(&mut tail_values);
-            }
 
                 Ok(values)
             } else {
-            unreachable!()
+                Ok(self.head(Some(size))?)
+            }
+        } else {
+            unreachable!("No dataframe found in print command")
         }
     }
 

crates/nu-protocol/src/dataframe/nu_groupby.rs

@@ -0,0 +1,54 @@
+use nu_source::Tag;
+use polars::frame::groupby::{GroupBy, GroupTuples};
+use serde::{Deserialize, Serialize};
+
+use super::NuDataFrame;
+use nu_errors::ShellError;
+
+use crate::{TaggedDictBuilder, Value};
+
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Serialize, Deserialize)]
+pub struct NuGroupBy {
+    dataframe: NuDataFrame,
+    by: Vec<String>,
+    groups: GroupTuples,
+}
+
+impl NuGroupBy {
+    pub fn new(dataframe: NuDataFrame, by: Vec<String>, groups: GroupTuples) -> Self {
+        NuGroupBy {
+            dataframe,
+            by,
+            groups,
+        }
+    }
+
+    pub fn to_groupby(&self) -> Result<GroupBy, ShellError> {
+        let df = match &self.dataframe.dataframe {
+            Some(df) => df,
+            None => unreachable!("No dataframe in nu_dataframe"),
+        };
+
+        let by = df.select_series(&self.by).map_err(|e| {
+            ShellError::labeled_error("Error creating groupby", format!("{}", e), Tag::unknown())
+        })?;
+
+        Ok(GroupBy::new(df, by, self.groups.clone(), None))
+    }
+
+    pub fn print(&self) -> Result<Vec<Value>, ShellError> {
+        let mut values: Vec<Value> = Vec::new();
+
+        let mut data = TaggedDictBuilder::new(Tag::unknown());
+        data.insert_value("property", "dataframe");
+        data.insert_value("value", self.dataframe.name.as_ref());
+        values.push(data.into_value());
+
+        let mut data = TaggedDictBuilder::new(Tag::unknown());
+        data.insert_value("property", "group by");
+        data.insert_value("value", self.by.join(", "));
+        values.push(data.into_value());
+
+        Ok(values)
+    }
+}

crates/nu-protocol/src/value.rs

@@ -31,7 +31,7 @@ use std::path::PathBuf;
 use std::time::SystemTime;
 
 #[cfg(feature = "dataframe")]
-use crate::dataframe::NuDataFrame;
+use crate::dataframe::PolarsData;
 
 /// The core structured values that flow through a pipeline
 #[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Serialize, Deserialize)]
@@ -54,7 +54,7 @@ pub enum UntaggedValue {
     /// Data option that holds the polars structs required to to data
     /// manipulation and operations using polars dataframes
     #[cfg(feature = "dataframe")]
-    DataFrame(NuDataFrame),
+    DataFrame(PolarsData),
 }
 
 impl UntaggedValue {

crates/nu-protocol/src/value/primitive.rs

@@ -364,8 +364,8 @@ macro_rules! from_native_to_primitive {
     ($native_type:ty, $primitive_type:expr, $converter: expr) => {
         // e.g. from u32 -> Primitive
         impl From<$native_type> for Primitive {
-            fn from(int: $native_type) -> Primitive {
+            fn from(value: $native_type) -> Primitive {
-                if let Some(i) = $converter(int) {
+                if let Some(i) = $converter(value) {
                     $primitive_type(i)
                 } else {
                     unreachable!("Internal error: protocol did not use compatible decimal")