nu_command/matrix/
get_row.rs

1use crate::matrix::MatrixValue;
2use nu_engine::command_prelude::*;
3
4#[derive(Clone)]
5pub struct MatrixGetRow;
6
7impl Command for MatrixGetRow {
8    fn name(&self) -> &str {
9        "matrix get-row"
10    }
11
12    fn signature(&self) -> Signature {
13        Signature::build("matrix get-row")
14            .input_output_types(vec![(
15                Type::Custom("matrix".into()),
16                Type::List(Box::new(Type::Float)),
17            )])
18            .required(
19                "index",
20                SyntaxShape::Int,
21                "The row index to extract (0-based).",
22            )
23            .category(Category::Filters)
24    }
25
26    fn description(&self) -> &str {
27        "Extract a row from a matrix."
28    }
29
30    fn search_terms(&self) -> Vec<&str> {
31        vec![]
32    }
33
34    fn run(
35        &self,
36        engine_state: &EngineState,
37        stack: &mut Stack,
38        call: &Call,
39        input: PipelineData,
40    ) -> Result<PipelineData, ShellError> {
41        let head = call.head;
42        let index: usize = call.req::<i64>(engine_state, stack, 0)? as usize;
43        let matrix = MatrixValue::from_value(&input.into_value(head)?)?;
44
45        if index >= matrix.array.shape()[0] {
46            return Err(ShellError::Generic(
47                nu_protocol::shell_error::generic::GenericError::new(
48                    "Index out of bounds",
49                    format!(
50                        "row index {} is out of bounds, matrix has {} rows",
51                        index,
52                        matrix.array.shape()[0]
53                    ),
54                    head,
55                ),
56            ));
57        }
58
59        let row = matrix.array.index_axis(ndarray::Axis(0), index);
60        let vals: Vec<Value> = row.iter().map(|v| Value::float(*v, head)).collect();
61        Ok(Value::list(vals, head).into_pipeline_data())
62    }
63
64    fn examples(&self) -> Vec<Example<'static>> {
65        vec![
66            Example {
67                description: "Get the first row of a 2x3 matrix",
68                example: "matrix zeros 2 3 | matrix set-row 0 [1.0 2.0 3.0] | matrix get-row 0 | to nuon",
69                result: Some(Value::test_string("[1.0, 2.0, 3.0]")),
70            },
71            Example {
72                description: "Get the second row of a 2x2 identity matrix",
73                example: "matrix identity 2 | matrix get-row 1 | to nuon",
74                result: Some(Value::test_string("[0.0, 1.0]")),
75            },
76        ]
77    }
78}
79
80#[cfg(test)]
81mod test {
82    use super::*;
83
84    #[test]
85    fn test_examples() -> nu_test_support::Result {
86        nu_test_support::test().examples(MatrixGetRow)
87    }
88}
nu_command/matrix/get_row.rs

nu_command/matrix/
get_row.rs
