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Create general functions.
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//! This module contains functions for calculating statistics. | ||
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use std::{ | ||
collections::HashMap, | ||
hash::Hash, | ||
ops::{Add, Sub}, | ||
}; | ||
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/// Returns the mean of a list of values. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::mean; | ||
/// let values = vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0]; | ||
/// assert_eq!(mean(&values), 3.5); | ||
/// ``` | ||
pub fn mean<T: Into<f64> + Copy>(data: &[T]) -> f64 { | ||
let mut sum = 0.0; | ||
for &x in data { | ||
sum += x.into(); | ||
} | ||
sum / data.len() as f64 | ||
} | ||
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/// Returns the median of a list of values | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::median; | ||
/// let values = vec![1.0, 9.0, 2.5, 3.0, 2.0, 8.0]; | ||
/// assert_eq!(median(&values), Some(2.75)); | ||
/// ``` | ||
pub fn median<T: Into<f64> + Copy>(data: &[T]) -> Option<f64> { | ||
if data.is_empty() { | ||
return None; | ||
} | ||
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let mut sorted = data.iter().map(|&x| x.into()).collect::<Vec<_>>(); | ||
sorted.sort_by(|a, b| a.partial_cmp(b).unwrap()); | ||
let mid = sorted.len() / 2; | ||
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if sorted.len() % 2 == 0 { | ||
Some((sorted[mid - 1] + sorted[mid]) / 2.0) | ||
} else { | ||
Some(sorted[mid]) | ||
} | ||
} | ||
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/// Returns the mode of a list of values. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::mode; | ||
/// let values = vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 9]; | ||
/// assert_eq!(mode(&values), Some(9)); | ||
/// ``` | ||
pub fn mode<T: Copy + Eq + Hash>(data: &[T]) -> Option<T> { | ||
if data.is_empty() { | ||
return None; | ||
} | ||
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let mut counts: HashMap<T, i64> = HashMap::new(); | ||
data.iter().copied().max_by_key(|&x| { | ||
let count = counts.entry(x).or_insert(0); | ||
*count += 1; | ||
*count | ||
}) | ||
} | ||
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/// Returns the sample variance of a list of values. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::var; | ||
/// let values = vec![1.0, 2.0, 3.0, 4.0, 5.0]; | ||
/// assert_eq!(var(&values), 2.5); | ||
/// ``` | ||
pub fn var<T: Into<f64> + Copy + Add + Sub>(data: &[T]) -> f64 { | ||
let mean = mean(data); | ||
data.iter() | ||
.map(|&x| ((x.into() - mean).powi(2)) / (data.len() - 1) as f64) | ||
.sum() | ||
} | ||
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/// Returns the population variance of a list of values. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::pop_var; | ||
/// let values = vec![1.0, 2.0, 3.0, 4.0, 5.0]; | ||
/// assert_eq!(pop_var(&values), 2.0); | ||
/// ``` | ||
pub fn pop_var<T: Into<f64> + Copy + Add + Sub>(data: &[T]) -> f64 { | ||
let mean = mean(data); | ||
data.iter() | ||
.map(|&x| ((x.into() - mean).powi(2)) / data.len() as f64) | ||
.sum() | ||
} | ||
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/// Returns the sample standard deviation of a list of values. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::std; | ||
/// let values = vec![1.0, 2.0, 3.0, 4.0, 5.0]; | ||
/// assert_eq!(std(&values), 1.5811388300841898); | ||
/// ``` | ||
pub fn std<T: Into<f64> + Copy + Add + Sub>(data: &[T]) -> f64 { | ||
var(data).sqrt() | ||
} | ||
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/// Returns the population standard deviation of a list of values. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::pop_std; | ||
/// let values = vec![1.0, 2.0, 3.0, 4.0, 5.0]; | ||
/// assert_eq!(pop_std(&values), 1.4142135623730951); | ||
/// ``` | ||
pub fn pop_std<T: Into<f64> + Copy + Add + Sub>(data: &[T]) -> f64 { | ||
pop_var(data).sqrt() | ||
} | ||
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/// Returns the sample standard error of a list of values. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::mean_std_err; | ||
/// let values = vec![1.0, 2.0, 3.0, 4.0, 5.0]; | ||
/// assert_eq!(mean_std_err(&values), 0.7071067811865476); | ||
/// ``` | ||
pub fn mean_std_err<T: Into<f64> + Copy + Add + Sub>(data: &[T]) -> f64 { | ||
std(data) / (data.len() as f64).sqrt() | ||
} | ||
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/// Returns the mean confidence interval of a list of values. | ||
/// Confidence level is a value between 0 and 1. | ||
/// | ||
/// # Examples | ||
/// | ||
/// ``` | ||
/// use engram::mean_ci; | ||
/// let values = vec![1.0, 2.0, 3.0, 4.0, 5.0]; | ||
/// assert_eq!(mean_ci(&values, 0.95).unwrap(), (2.32824855787278, 3.67175144212722)); | ||
/// ``` | ||
#[derive(Debug)] | ||
pub enum MeanCIError { | ||
EmptyData, | ||
InvalidConfidence, | ||
} | ||
pub fn mean_ci<T: Into<f64> + Copy + Add + Sub>( | ||
data: &[T], | ||
confidence: f64, | ||
) -> Result<(f64, f64), MeanCIError> { | ||
if confidence <= 0.0 || confidence >= 1.0 { | ||
return Err(MeanCIError::EmptyData); | ||
} | ||
if confidence <= 0.0 || confidence >= 1.0 { | ||
return Err(MeanCIError::InvalidConfidence); | ||
} | ||
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let mean = mean(data); | ||
let mean_std_err = mean_std_err(data); | ||
let z_std_err = confidence * mean_std_err; | ||
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Ok((mean - z_std_err, mean + z_std_err)) | ||
} |