append dataframes (#3839)

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

@@ -0,0 +1,138 @@
+use crate::prelude::*;
+use nu_engine::WholeStreamCommand;
+use nu_errors::ShellError;
+use nu_protocol::{
+    dataframe::{Axis, Column, NuDataFrame},
+    Signature, SyntaxShape, UntaggedValue, Value,
+};
+use nu_source::Tagged;
+
+pub struct DataFrame;
+
+impl WholeStreamCommand for DataFrame {
+    fn name(&self) -> &str {
+        "dataframe append"
+    }
+
+    fn usage(&self) -> &str {
+        "[DataFrame] Appends a new dataframe"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("dataframe append")
+            .required_named(
+                "other",
+                SyntaxShape::Any,
+                "dataframe to be appended",
+                Some('o'),
+            )
+            .required_named(
+                "axis",
+                SyntaxShape::String,
+                "row or col axis orientation",
+                Some('a'),
+            )
+    }
+
+    fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
+        command(args)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Appends a dataframe as new columns",
+                example: r#"let a = ([[a b]; [1 2] [3 4]] | dataframe to-df);
+    $a | dataframe append -o $a -a row"#,
+                result: Some(vec![NuDataFrame::try_from_columns(
+                    vec![
+                        Column::new(
+                            "a".to_string(),
+                            vec![UntaggedValue::int(1).into(), UntaggedValue::int(3).into()],
+                        ),
+                        Column::new(
+                            "b".to_string(),
+                            vec![UntaggedValue::int(2).into(), UntaggedValue::int(4).into()],
+                        ),
+                        Column::new(
+                            "a_x".to_string(),
+                            vec![UntaggedValue::int(1).into(), UntaggedValue::int(3).into()],
+                        ),
+                        Column::new(
+                            "b_x".to_string(),
+                            vec![UntaggedValue::int(2).into(), UntaggedValue::int(4).into()],
+                        ),
+                    ],
+                    &Span::default(),
+                )
+                .expect("simple df for test should not fail")
+                .into_value(Tag::default())]),
+            },
+            Example {
+                description: "Appends a dataframe merging at the end of columns",
+                example: r#"let a = ([[a b]; [1 2] [3 4]] | dataframe to-df);
+    $a | dataframe append -o $a -a col"#,
+                result: Some(vec![NuDataFrame::try_from_columns(
+                    vec![
+                        Column::new(
+                            "a".to_string(),
+                            vec![
+                                UntaggedValue::int(1).into(),
+                                UntaggedValue::int(3).into(),
+                                UntaggedValue::int(1).into(),
+                                UntaggedValue::int(3).into(),
+                            ],
+                        ),
+                        Column::new(
+                            "b".to_string(),
+                            vec![
+                                UntaggedValue::int(2).into(),
+                                UntaggedValue::int(4).into(),
+                                UntaggedValue::int(2).into(),
+                                UntaggedValue::int(4).into(),
+                            ],
+                        ),
+                    ],
+                    &Span::default(),
+                )
+                .expect("simple df for test should not fail")
+                .into_value(Tag::default())]),
+            },
+        ]
+    }
+}
+
+fn command(mut args: CommandArgs) -> Result<OutputStream, ShellError> {
+    let tag = args.call_info.name_tag.clone();
+    let other: Value = args.req_named("other")?;
+    let axis: Tagged<String> = args.req_named("axis")?;
+
+    let axis = Axis::try_from_str(axis.item.as_str(), &axis.tag.span)?;
+
+    let df_other = match other.value {
+        UntaggedValue::DataFrame(df) => Ok(df),
+        _ => Err(ShellError::labeled_error(
+            "Incorrect type",
+            "can only append a dataframe to a dataframe",
+            other.tag.span,
+        )),
+    }?;
+
+    let (df, _) = NuDataFrame::try_from_stream(&mut args.input, &tag.span)?;
+
+    let df_new = df.append_df(&df_other, axis, &tag.span)?;
+    Ok(OutputStream::one(df_new.into_value(tag)))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::DataFrame;
+    use super::ShellError;
+
+    #[test]
+    fn examples_work_as_expected() -> Result<(), ShellError> {
+        use crate::examples::test_dataframe as test_examples;
+
+        test_examples(DataFrame {})
+    }
+}

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

@@ -1,4 +1,5 @@
 pub mod aggregate;
+pub mod append;
 pub mod column;
 pub mod command;
 pub mod drop;
@@ -31,6 +32,7 @@ pub mod where_;
 pub mod with_column;
 
 pub use aggregate::DataFrame as DataFrameAggregate;
+pub use append::DataFrame as DataFrameAppend;
 pub use column::DataFrame as DataFrameColumn;
 pub use command::Command as DataFrame;
 pub use drop::DataFrame as DataFrameDrop;

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

@@ -25,9 +25,9 @@ pub use conversions::*;
 pub use core_commands::*;
 #[cfg(feature = "dataframe")]
 pub use dataframe::{
-    DataFrame, DataFrameAggregate, DataFrameAllFalse, DataFrameAllTrue, DataFrameArgMax,
-    DataFrameArgMin, DataFrameArgSort, DataFrameArgTrue, DataFrameArgUnique, DataFrameColumn,
-    DataFrameConcatenate, DataFrameContains, DataFrameDTypes, DataFrameDrop,
+    DataFrame, DataFrameAggregate, DataFrameAllFalse, DataFrameAllTrue, DataFrameAppend,
+    DataFrameArgMax, DataFrameArgMin, DataFrameArgSort, DataFrameArgTrue, DataFrameArgUnique,
+    DataFrameColumn, DataFrameConcatenate, DataFrameContains, DataFrameDTypes, DataFrameDrop,
     DataFrameDropDuplicates, DataFrameDropNulls, DataFrameDummies, DataFrameFilter, DataFrameFirst,
     DataFrameGet, DataFrameGroupBy, DataFrameIsDuplicated, DataFrameIsIn, DataFrameIsNotNull,
     DataFrameIsNull, DataFrameIsUnique, DataFrameJoin, DataFrameLast, DataFrameList, DataFrameMelt,