nushell/crates/nu-command/src/dataframe/eager/take.rs

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use nu_engine::CallExt;
use nu_protocol::{
ast::Call,
engine::{Command, EngineState, Stack},
Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
};
use polars::prelude::DataType;
use crate::dataframe::values::Column;
use super::super::values::NuDataFrame;
#[derive(Clone)]
pub struct TakeDF;
impl Command for TakeDF {
fn name(&self) -> &str {
"take"
}
fn usage(&self) -> &str {
"Creates new dataframe using the given indices"
}
fn signature(&self) -> Signature {
Signature::build(self.name())
.required(
"indices",
SyntaxShape::Any,
"list of indices used to take data",
)
.category(Category::Custom("dataframe".into()))
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Takes selected rows from dataframe",
example: r#"let df = ([[a b]; [4 1] [5 2] [4 3]] | to-df);
let indices = ([0 2] | to-df);
$df | take $indices"#,
result: Some(
NuDataFrame::try_from_columns(vec![
Column::new(
"a".to_string(),
vec![Value::test_int(4), Value::test_int(4)],
),
Column::new(
"b".to_string(),
vec![Value::test_int(1), Value::test_int(3)],
),
])
.expect("simple df for test should not fail")
.into_value(Span::test_data()),
),
},
Example {
description: "Takes selected rows from series",
example: r#"let series = ([4 1 5 2 4 3] | to-df);
let indices = ([0 2] | to-df);
$series | take $indices"#,
result: Some(
NuDataFrame::try_from_columns(vec![Column::new(
"0".to_string(),
vec![Value::test_int(4), Value::test_int(5)],
)])
.expect("simple df for test should not fail")
.into_value(Span::test_data()),
),
},
]
}
fn input_type(&self) -> Type {
Type::Custom("dataframe".into())
}
fn output_type(&self) -> Type {
Type::Custom("dataframe".into())
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
command(engine_state, stack, call, input)
}
}
fn command(
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let index_value: Value = call.req(engine_state, stack, 0)?;
let index_span = index_value.span()?;
let index = NuDataFrame::try_from_value(index_value)?.as_series(index_span)?;
let casted = match index.dtype() {
DataType::UInt32 | DataType::UInt64 | DataType::Int32 | DataType::Int64 => {
index.cast(&DataType::UInt32).map_err(|e| {
ShellError::GenericError(
"Error casting index list".into(),
e.to_string(),
Some(index_span),
None,
Vec::new(),
)
})
}
_ => Err(ShellError::GenericError(
"Incorrect type".into(),
"Series with incorrect type".into(),
Some(call.head),
Some("Consider using a Series with type int type".into()),
Vec::new(),
)),
}?;
let indices = casted.u32().map_err(|e| {
ShellError::GenericError(
"Error casting index list".into(),
e.to_string(),
Some(index_span),
None,
Vec::new(),
)
})?;
NuDataFrame::try_from_pipeline(input, call.head).and_then(|df| {
df.as_ref()
.take(indices)
.map_err(|e| {
ShellError::GenericError(
"Error taking values".into(),
e.to_string(),
Some(call.head),
None,
Vec::new(),
)
})
.map(|df| PipelineData::Value(NuDataFrame::dataframe_into_value(df, call.head), None))
})
}
#[cfg(test)]
mod test {
use super::super::super::test_dataframe::test_dataframe;
use super::*;
#[test]
fn test_examples() {
test_dataframe(vec![Box::new(TakeDF {})])
}
}