2021-11-03 22:24:15 +01:00
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use crate::math::avg::average;
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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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2021-11-17 05:22:37 +01:00
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use nu_protocol::{Category, Example, PipelineData, ShellError, Signature, Span, Value};
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2021-11-03 22:24:15 +01:00
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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 median"
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}
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fn signature(&self) -> Signature {
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2021-11-17 05:22:37 +01:00
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Signature::build("math median").category(Category::Math)
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2021-11-03 22:24:15 +01:00
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}
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fn usage(&self) -> &str {
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"Gets the median of a list of numbers"
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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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run_with_function(call, input, median)
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}
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fn examples(&self) -> Vec<Example> {
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vec![Example {
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description: "Get the median of a list of numbers",
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example: "[3 8 9 12 12 15] | math median",
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result: Some(Value::Float {
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val: 10.5,
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span: Span::unknown(),
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}),
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}]
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}
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}
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enum Pick {
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MedianAverage,
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Median,
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}
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pub fn median(values: &[Value], head: &Span) -> Result<Value, ShellError> {
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let take = if values.len() % 2 == 0 {
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Pick::MedianAverage
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} else {
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Pick::Median
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};
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let mut sorted = vec![];
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for item in values {
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sorted.push(item.clone());
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}
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if let Some(Err(values)) = values
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.windows(2)
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.map(|elem| {
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if elem[0].partial_cmp(&elem[1]).is_none() {
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return Err(ShellError::OperatorMismatch {
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op_span: *head,
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lhs_ty: elem[0].get_type(),
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lhs_span: elem[0].span()?,
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rhs_ty: elem[1].get_type(),
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rhs_span: elem[1].span()?,
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});
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}
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Ok(elem[0].partial_cmp(&elem[1]).unwrap())
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})
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.find(|elem| elem.is_err())
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{
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return Err(values);
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}
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sorted.sort_by(|a, b| a.partial_cmp(b).unwrap());
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match take {
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Pick::Median => {
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let idx = (values.len() as f64 / 2.0).floor() as usize;
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let out = sorted
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.get(idx)
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.ok_or_else(|| ShellError::UnsupportedInput("Empty input".to_string(), *head))?;
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Ok(out.clone())
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}
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Pick::MedianAverage => {
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let idx_end = (values.len() / 2) as usize;
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let idx_start = idx_end - 1;
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let left = sorted
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.get(idx_start)
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.ok_or_else(|| ShellError::UnsupportedInput("Empty input".to_string(), *head))?
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.clone();
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let right = sorted
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.get(idx_end)
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.ok_or_else(|| ShellError::UnsupportedInput("Empty input".to_string(), *head))?
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.clone();
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average(&[left, right], head)
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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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