nu-command 0.75.0

Nushell's built-in commands
Documentation 
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
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153

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",
            )
            .input_type(Type::Custom("dataframe".into()))
            .output_type(Type::Custom("dataframe".into()))
            .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]] | into df);
    let indices = ([0 2] | into 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] | into df);
    let indices = ([0 2] | into 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 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 {})])
    }
}