nu_plugin_polars 0.112.0

Nushell dataframe plugin commands based on polars.
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use crate::PolarsPlugin;
use crate::values::{Column, CustomValueSupport, NuDataFrame, PolarsPluginType};

use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
use nu_protocol::{
    Category, Example, LabeledError, PipelineData, ShellError, Signature, Span, Value,
    shell_error::generic::GenericError,
};

#[derive(Clone)]
pub struct AllFalse;

impl PluginCommand for AllFalse {
    type Plugin = PolarsPlugin;

    fn name(&self) -> &str {
        "polars all-false"
    }

    fn description(&self) -> &str {
        "Returns true if all values are false."
    }

    fn signature(&self) -> Signature {
        Signature::build(self.name())
            .category(Category::Custom("dataframe".into()))
            .input_output_types(vec![
                (
                    PolarsPluginType::NuDataFrame.into(),
                    PolarsPluginType::NuDataFrame.into(),
                ),
                (
                    PolarsPluginType::NuLazyFrame.into(),
                    PolarsPluginType::NuLazyFrame.into(),
                ),
            ])
    }

    fn examples(&self) -> Vec<Example<'_>> {
        vec![
            Example {
                description: "Returns true if all values are false",
                example: "[false false false] | polars into-df | polars all-false",
                result: Some(
                    NuDataFrame::try_from_columns(
                        vec![Column::new(
                            "all_false".to_string(),
                            vec![Value::test_bool(true)],
                        )],
                        None,
                        Span::test_data(),
                    )
                    .expect("simple df for test should not fail")
                    .into_value(Span::test_data()),
                ),
            },
            Example {
                description: "Checks the result from a comparison",
                example: r#"let s = ([5 6 2 10] | polars into-df);
    let res = ($s > 9);
    $res | polars all-false"#,
                result: Some(
                    NuDataFrame::try_from_columns(
                        vec![Column::new(
                            "all_false".to_string(),
                            vec![Value::test_bool(false)],
                        )],
                        None,
                        Span::test_data(),
                    )
                    .expect("simple df for test should not fail")
                    .into_value(Span::test_data()),
                ),
            },
        ]
    }

    fn run(
        &self,
        plugin: &Self::Plugin,
        engine: &EngineInterface,
        call: &EvaluatedCall,
        mut input: PipelineData,
    ) -> Result<PipelineData, LabeledError> {
        let metadata = input.take_metadata();
        command(plugin, engine, call, input)
            .map_err(LabeledError::from)
            .map(|pd| pd.set_metadata(metadata))
    }
}

fn command(
    plugin: &PolarsPlugin,
    engine: &EngineInterface,
    call: &EvaluatedCall,
    input: PipelineData,
) -> Result<PipelineData, ShellError> {
    let df = NuDataFrame::try_from_pipeline_coerce(plugin, input, call.head)?;

    let series = df.as_series(call.head)?;
    let bool = series.bool().map_err(|_| {
        ShellError::Generic(GenericError::new(
            "Error converting to bool",
            "all-false only works with series of type bool",
            call.head,
        ))
    })?;

    let value = Value::bool(!bool.any(), call.head);

    let df = NuDataFrame::try_from_columns(
        vec![Column::new("all_false".to_string(), vec![value])],
        None,
        call.head,
    )?;
    df.to_pipeline_data(plugin, engine, call.head)
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::test::test_polars_plugin_command;

    #[test]
    fn test_examples() -> Result<(), ShellError> {
        test_polars_plugin_command(&AllFalse)
    }
}