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9996e4a1f8
# Description Continuing from #12568, this PR further reduces the size of `Expr` from 64 to 40 bytes. It also reduces `Expression` from 128 to 96 bytes and `Type` from 32 to 24 bytes. This was accomplished by: - for `Expr` with multiple fields (e.g., `Expr::Thing(A, B, C)`), merging the fields into new AST struct types and then boxing this struct (e.g. `Expr::Thing(Box<ABC>)`). - replacing `Vec<T>` with `Box<[T]>` in multiple places. `Expr`s and `Expression`s should rarely be mutated, if at all, so this optimization makes sense. By reducing the size of these types, I didn't notice a large performance improvement (at least compared to #12568). But this PR does reduce the memory usage of nushell. My config is somewhat light so I only noticed a difference of 1.4MiB (38.9MiB vs 37.5MiB). --------- Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>
103 lines
3.1 KiB
Rust
103 lines
3.1 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_engine::command_prelude::*;
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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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.input_output_types(vec![
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(Type::List(Box::new(Type::Number)), Type::Number),
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(Type::table(), Type::record()),
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(Type::record(), Type::record()),
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])
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.switch(
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"sample",
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"calculate sample standard deviation (i.e. using N-1 as the denominator)",
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Some('s'),
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)
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.allow_variants_without_examples(true)
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.category(Category::Math)
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}
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fn usage(&self) -> &str {
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"Returns the standard deviation of a list of numbers, or of each column in a table."
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}
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fn search_terms(&self) -> Vec<&str> {
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vec![
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"SD",
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"standard",
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"deviation",
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"dispersion",
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"variation",
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"statistics",
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]
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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<PipelineData, ShellError> {
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let sample = call.has_flag(engine_state, stack, "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: "Compute the standard deviation of a list of numbers",
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example: "[1 2 3 4 5] | math stddev",
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result: Some(Value::test_float(std::f64::consts::SQRT_2)),
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},
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Example {
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description: "Compute the sample standard deviation of a list of numbers",
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example: "[1 2 3 4 5] | math stddev --sample",
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result: Some(Value::test_float(1.5811388300841898)),
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},
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Example {
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description: "Compute the standard deviation of each column in a table",
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example: "[[a b]; [1 2] [3 4]] | math stddev",
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result: Some(Value::test_record(record! {
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"a" => Value::test_int(1),
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"b" => Value::test_int(1),
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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, Span) -> Result<Value, ShellError> {
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move |values: &[Value], span: Span, head: Span| {
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// variance() produces its own usable error, so we can use `?` to propagated the error.
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let variance = variance(sample)(values, span, head)?;
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let val_span = variance.span();
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match variance {
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Value::Float { val, .. } => Ok(Value::float(val.sqrt(), val_span)),
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Value::Int { val, .. } => Ok(Value::float((val as f64).sqrt(), val_span)),
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other => Ok(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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