nu_plugin_polars 0.113.0

Nushell dataframe plugin commands based on polars.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111

use crate::PolarsPlugin;
use crate::dataframe::values::NuExpression;
use crate::values::{
    CustomValueSupport, NuDataFrame, PolarsPluginObject, PolarsPluginType, cant_convert_err,
};
use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
use nu_protocol::{Category, Example, LabeledError, PipelineData, ShellError, Signature, Span};
use polars::df;

pub struct ExprNot;

impl PluginCommand for ExprNot {
    type Plugin = PolarsPlugin;

    fn name(&self) -> &str {
        "polars expr-not"
    }

    fn description(&self) -> &str {
        "Creates a not expression."
    }

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

    fn examples(&self) -> Vec<Example<'_>> {
        vec![
            Example {
                description: "Creates a not expression",
                example: "(polars col a) > 2) | polars expr-not",
                result: None,
            },
            Example {
                description: "Adds a column showing which values of col a are not greater than 2",
                example: "[[a]; [1] [2] [3] [4] [5]] | polars into-df 
                    | polars with-column [(((polars col a) > 2)
                    | polars expr-not
                    | polars as a_expr_not)]
                    | polars collect
                    | polars sort-by a",
                result: Some(
                    NuDataFrame::from(
                        df!(
                            "a" => [1, 2, 3, 4, 5],
                            "b" => [true, true, false, false, false]
                        )
                        .expect("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();
        let value = input.into_value(call.head)?;
        match PolarsPluginObject::try_from_value(plugin, &value)? {
            PolarsPluginObject::NuExpression(expr) => command_expr(plugin, engine, call, expr),
            PolarsPluginObject::NuSelector(selector) => {
                let expr = selector.into_expr();
                command_expr(plugin, engine, call, expr)
            }
            _ => Err(cant_convert_err(
                &value,
                &[PolarsPluginType::NuExpression, PolarsPluginType::NuSelector],
            )),
        }
        .map_err(LabeledError::from)
        .map(|pd| pd.set_metadata(metadata))
    }
}

fn command_expr(
    plugin: &PolarsPlugin,
    engine: &EngineInterface,
    call: &EvaluatedCall,
    expr: NuExpression,
) -> Result<PipelineData, ShellError> {
    NuExpression::from(expr.into_polars().not()).to_pipeline_data(plugin, engine, call.head)
}

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

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