nushell/crates/nu-command/src/math/stddev.rs
Jérémy Audiger 99076af18b
Use imported names in Command::run signatures (#7967)
# Description

_(Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
changes.)_

I opened this PR to unify the run command method. It's mainly to improve
consistency across the tree.

# User-Facing Changes

None.

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
2023-02-05 22:17:46 +01:00

97 lines
2.8 KiB
Rust

use super::variance::compute_variance as variance;
use crate::math::utils::run_with_function;
use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Type, Value};
#[derive(Clone)]
pub struct SubCommand;
impl Command for SubCommand {
fn name(&self) -> &str {
"math stddev"
}
fn signature(&self) -> Signature {
Signature::build("math stddev")
.input_output_types(vec![(Type::List(Box::new(Type::Number)), Type::Number)])
.switch(
"sample",
"calculate sample standard deviation (i.e. using N-1 as the denominator)",
Some('s'),
)
.category(Category::Math)
}
fn usage(&self) -> &str {
"Returns the standard deviation of a list of numbers, or of each column in a table"
}
fn search_terms(&self) -> Vec<&str> {
vec![
"SD",
"standard",
"deviation",
"dispersion",
"variation",
"statistics",
]
}
fn run(
&self,
_engine_state: &EngineState,
_stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let sample = call.has_flag("sample");
run_with_function(call, input, compute_stddev(sample))
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Compute the standard deviation of a list of numbers",
example: "[1 2 3 4 5] | math stddev",
result: Some(Value::test_float(std::f64::consts::SQRT_2)),
},
Example {
description: "Compute the sample standard deviation of a list of numbers",
example: "[1 2 3 4 5] | math stddev -s",
result: Some(Value::test_float(1.5811388300841898)),
},
]
}
}
pub fn compute_stddev(sample: bool) -> impl Fn(&[Value], Span, &Span) -> Result<Value, ShellError> {
move |values: &[Value], span: Span, head: &Span| {
let variance = variance(sample)(values, span, head);
match variance {
Ok(Value::Float { val, span }) => Ok(Value::Float {
val: val.sqrt(),
span,
}),
Ok(Value::Int { val, span }) => Ok(Value::Float {
val: (val as f64).sqrt(),
span,
}),
// variance() produces its own usable error, which can simply be propagated.
Err(e) => Err(e),
other => other,
}
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(SubCommand {})
}
}