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

use nu_engine::CallExt;
use nu_protocol::{
    ast::Call,
    engine::{Command, EngineState, Stack},
    Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type,
};

use super::super::values::NuDataFrame;

#[derive(Clone)]
pub struct SampleDF;

impl Command for SampleDF {
    fn name(&self) -> &str {
        "sample"
    }

    fn usage(&self) -> &str {
        "Create sample dataframe"
    }

    fn signature(&self) -> Signature {
        Signature::build(self.name())
            .named(
                "n-rows",
                SyntaxShape::Int,
                "number of rows to be taken from dataframe",
                Some('n'),
            )
            .named(
                "fraction",
                SyntaxShape::Number,
                "fraction of dataframe to be taken",
                Some('f'),
            )
            .named(
                "seed",
                SyntaxShape::Number,
                "seed for the selection",
                Some('s'),
            )
            .switch("replace", "sample with replace", Some('e'))
            .switch("shuffle", "shuffle sample", Some('u'))
            .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: "Sample rows from dataframe",
                example: "[[a b]; [1 2] [3 4]] | into df | sample -n 1",
                result: None, // No expected value because sampling is random
            },
            Example {
                description: "Shows sample row using fraction and replace",
                example: "[[a b]; [1 2] [3 4] [5 6]] | into df | sample -f 0.5 -e",
                result: None, // No expected value because sampling is random
            },
        ]
    }

    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 rows: Option<Spanned<usize>> = call.get_flag(engine_state, stack, "n-rows")?;
    let fraction: Option<Spanned<f64>> = call.get_flag(engine_state, stack, "fraction")?;
    let seed: Option<u64> = call
        .get_flag::<i64>(engine_state, stack, "seed")?
        .map(|val| val as u64);
    let replace: bool = call.has_flag("replace");
    let shuffle: bool = call.has_flag("shuffle");

    let df = NuDataFrame::try_from_pipeline(input, call.head)?;

    match (rows, fraction) {
        (Some(rows), None) => df
            .as_ref()
            .sample_n(rows.item, replace, shuffle, seed)
            .map_err(|e| {
                ShellError::GenericError(
                    "Error creating sample".into(),
                    e.to_string(),
                    Some(rows.span),
                    None,
                    Vec::new(),
                )
            }),
        (None, Some(frac)) => df
            .as_ref()
            .sample_frac(frac.item, replace, shuffle, seed)
            .map_err(|e| {
                ShellError::GenericError(
                    "Error creating sample".into(),
                    e.to_string(),
                    Some(frac.span),
                    None,
                    Vec::new(),
                )
            }),
        (Some(_), Some(_)) => Err(ShellError::GenericError(
            "Incompatible flags".into(),
            "Only one selection criterion allowed".into(),
            Some(call.head),
            None,
            Vec::new(),
        )),
        (None, None) => Err(ShellError::GenericError(
            "No selection".into(),
            "No selection criterion was found".into(),
            Some(call.head),
            Some("Perhaps you want to use the flag -n or -f".into()),
            Vec::new(),
        )),
    }
    .map(|df| PipelineData::Value(NuDataFrame::dataframe_into_value(df, call.head), None))
}