forked from extern/nushell
84 lines
2.6 KiB
Rust
84 lines
2.6 KiB
Rust
use super::variance::compute_variance as variance;
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use crate::math::utils::run_with_function;
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use nu_protocol::ast::Call;
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use nu_protocol::engine::{Command, EngineState, Stack};
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use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
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#[derive(Clone)]
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pub struct SubCommand;
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impl Command for SubCommand {
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fn name(&self) -> &str {
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"math stddev"
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}
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fn signature(&self) -> Signature {
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Signature::build("math stddev")
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.switch("sample", "calculate sample standard deviation", Some('s'))
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.category(Category::Math)
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}
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fn usage(&self) -> &str {
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"Finds the stddev of a list of numbers or tables"
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}
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fn run(
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&self,
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_engine_state: &EngineState,
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_stack: &mut Stack,
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call: &Call,
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input: PipelineData,
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) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
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let sample = call.has_flag("sample");
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run_with_function(call, input, compute_stddev(sample))
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Get the stddev of a list of numbers",
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example: "[1 2 3 4 5] | math stddev",
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result: Some(Value::Float {
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val: std::f64::consts::SQRT_2,
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span: Span::test_data(),
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}),
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},
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Example {
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description: "Get the sample stddev of a list of numbers",
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example: "[1 2 3 4 5] | math stddev -s",
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result: Some(Value::Float {
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val: 1.5811388300841898,
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span: Span::test_data(),
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}),
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},
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]
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}
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}
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pub fn compute_stddev(sample: bool) -> impl Fn(&[Value], &Span) -> Result<Value, ShellError> {
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move |values: &[Value], span: &Span| {
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let variance = variance(sample)(values, span);
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match variance {
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Ok(Value::Float { val, span }) => Ok(Value::Float { val: val.sqrt(), span }),
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Ok(Value::Int { val, span }) => Ok(Value::Float { val: (val as f64).sqrt(), span }),
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Err(ShellError::UnsupportedInput(_, err_span)) => Err(ShellError::UnsupportedInput(
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"Attempted to compute the standard deviation with an item that cannot be used for that.".to_string(),
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err_span,
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)),
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other => other
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}
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}
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn test_examples() {
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use crate::test_examples;
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test_examples(SubCommand {})
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}
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}
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