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use crate::commands::math::reducers::{reducer_for, Reduce};
use crate::commands::math::utils::run_with_function;
use crate::prelude::*;
use bigdecimal::FromPrimitive;
use nu_engine::WholeStreamCommand;
use nu_errors::ShellError;
use nu_protocol::{hir::Operator, Primitive, Signature, UntaggedValue, Value};
pub struct SubCommand;
impl WholeStreamCommand for SubCommand {
fn name(&self) -> &str {
"math median"
}
fn signature(&self) -> Signature {
Signature::build("math median")
}
fn usage(&self) -> &str {
"Gets the median of a list of numbers"
}
fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
run_with_function(args, median)
}
fn examples(&self) -> Vec<Example> {
vec![Example {
description: "Get the median of a list of numbers",
example: "echo [3 8 9 12 12 15] | math median",
result: Some(vec![UntaggedValue::decimal_from_float(
10.5,
Span::unknown(),
)
.into()]),
}]
}
}
enum Pick {
MedianAverage,
Median,
}
pub fn median(values: &[Value], name: &Tag) -> Result<Value, ShellError> {
let take = if values.len() % 2 == 0 {
Pick::MedianAverage
} else {
Pick::Median
};
let mut sorted = vec![];
for item in values {
sorted.push(item.clone());
}
crate::commands::filters::sort_by::sort(&mut sorted, &[], name, false)?;
match take {
Pick::Median => {
let idx = (values.len() as f64 / 2.0).floor() as usize;
let out = sorted.get(idx).ok_or_else(|| {
ShellError::labeled_error(
"could not extract value",
"could not extract value",
&name.span,
)
})?;
Ok(out.clone())
}
Pick::MedianAverage => {
let idx_end = (values.len() / 2) as usize;
let idx_start = idx_end - 1;
let left = sorted
.get(idx_start)
.ok_or_else(|| {
ShellError::labeled_error(
"could not extract value",
"could not extract value",
&name.span,
)
})?
.clone();
let right = sorted
.get(idx_end)
.ok_or_else(|| {
ShellError::labeled_error(
"could not extract value",
"could not extract value",
&name.span,
)
})?
.clone();
compute_average(&[left, right], name)
}
}
}
fn compute_average(values: &[Value], name: impl Into<Tag>) -> Result<Value, ShellError> {
let name = name.into();
let sum = reducer_for(Reduce::Summation);
let number = BigDecimal::from_usize(2).ok_or_else(|| {
ShellError::labeled_error(
"could not convert to big decimal",
"could not convert to big decimal",
&name,
)
})?;
let total_rows = UntaggedValue::decimal(number);
let total = sum(Value::nothing(), values.to_vec())?;
match total {
Value {
value: UntaggedValue::Primitive(Primitive::Filesize(num)),
..
} => {
let left = UntaggedValue::from(Primitive::Int(num as i64));
let result = nu_data::value::compute_values(Operator::Divide, &left, &total_rows);
match result {
Ok(UntaggedValue::Primitive(Primitive::Decimal(result))) => {
let (bi, _) = result.as_bigint_and_exponent();
let number = bi.to_u64();
match number {
Some(number) => Ok(UntaggedValue::filesize(number).into_value(name)),
None => Err(ShellError::labeled_error(
"Can't convert to filesize",
"can't convert to filesize",
name,
)),
}
}
Ok(_) => Err(ShellError::labeled_error(
"could not calculate median of non-numeric or unrelated types",
"source",
name,
)),
Err((left_type, right_type)) => Err(ShellError::coerce_error(
left_type.spanned(name.span),
right_type.spanned(name.span),
)),
}
}
Value {
value: UntaggedValue::Primitive(other),
..
} => {
let left = UntaggedValue::from(other);
let result = nu_data::value::compute_values(Operator::Divide, &left, &total_rows);
match result {
Ok(value) => Ok(value.into_value(name)),
Err((left_type, right_type)) => Err(ShellError::coerce_error(
left_type.spanned(name.span),
right_type.spanned(name.span),
)),
}
}
_ => Err(ShellError::labeled_error(
"could not calculate median of non-numeric or unrelated types",
"source",
name,
)),
}
}
#[cfg(test)]
mod tests {
use super::ShellError;
use super::SubCommand;
#[test]
fn examples_work_as_expected() -> Result<(), ShellError> {
use crate::examples::test as test_examples;
test_examples(SubCommand {})
}
}
