mirror of
https://github.com/nushell/nushell.git
synced 2025-04-29 23:54:26 +02:00
68adc4657f
This moves to predominantly supporting only lazy dataframes for most operations. It removes a lot of the type conversion between lazy and eager dataframes based on what was inputted into the command. For the most part the changes will mean: * You will need to run `polars collect` after performing operations * The into-lazy command has been removed as it is redundant. * When opening files a lazy frame will be outputted by default if the reader supports lazy frames A list of individual command changes can be found [here](https://hackmd.io/@nucore/Bk-3V-hW0) --------- Co-authored-by: Ian Manske <ian.manske@pm.me>
87 lines
2.6 KiB
Rust
87 lines
2.6 KiB
Rust
use crate::{
|
|
dataframe::values::{Column, NuDataFrame, NuExpression, NuLazyFrame},
|
|
values::CustomValueSupport,
|
|
PolarsPlugin,
|
|
};
|
|
|
|
use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
|
|
use nu_protocol::{
|
|
Category, Example, LabeledError, PipelineData, Signature, Span, SyntaxShape, Type, Value,
|
|
};
|
|
#[derive(Clone)]
|
|
pub struct LazySelect;
|
|
|
|
impl PluginCommand for LazySelect {
|
|
type Plugin = PolarsPlugin;
|
|
|
|
fn name(&self) -> &str {
|
|
"polars select"
|
|
}
|
|
|
|
fn usage(&self) -> &str {
|
|
"Selects columns from lazyframe."
|
|
}
|
|
|
|
fn signature(&self) -> Signature {
|
|
Signature::build(self.name())
|
|
.rest(
|
|
"select expressions",
|
|
SyntaxShape::Any,
|
|
"Expression(s) that define the column selection",
|
|
)
|
|
.input_output_type(
|
|
Type::Custom("dataframe".into()),
|
|
Type::Custom("dataframe".into()),
|
|
)
|
|
.category(Category::Custom("lazyframe".into()))
|
|
}
|
|
|
|
fn examples(&self) -> Vec<Example> {
|
|
vec![Example {
|
|
description: "Select a column from the dataframe",
|
|
example: "[[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select a",
|
|
result: Some(
|
|
NuDataFrame::try_from_columns(
|
|
vec![Column::new(
|
|
"a".to_string(),
|
|
vec![Value::test_int(6), Value::test_int(4), Value::test_int(2)],
|
|
)],
|
|
None,
|
|
)
|
|
.expect("simple df for test should not fail")
|
|
.into_value(Span::test_data()),
|
|
),
|
|
}]
|
|
}
|
|
|
|
fn run(
|
|
&self,
|
|
plugin: &Self::Plugin,
|
|
engine: &EngineInterface,
|
|
call: &EvaluatedCall,
|
|
input: PipelineData,
|
|
) -> Result<PipelineData, LabeledError> {
|
|
let vals: Vec<Value> = call.rest(0)?;
|
|
let expr_value = Value::list(vals, call.head);
|
|
let expressions = NuExpression::extract_exprs(plugin, expr_value)?;
|
|
|
|
let pipeline_value = input.into_value(call.head);
|
|
let lazy = NuLazyFrame::try_from_value_coerce(plugin, &pipeline_value)?;
|
|
let lazy = NuLazyFrame::new(lazy.to_polars().select(&expressions));
|
|
lazy.to_pipeline_data(plugin, engine, call.head)
|
|
.map_err(LabeledError::from)
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod test {
|
|
use crate::test::test_polars_plugin_command;
|
|
|
|
use super::*;
|
|
|
|
#[test]
|
|
fn test_examples() -> Result<(), nu_protocol::ShellError> {
|
|
test_polars_plugin_command(&LazySelect)
|
|
}
|
|
}
|