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use crate::*;
#[derive(Debug, Clone, PartialEq)]
pub struct Histogram {
total: usize,
bins: Box<[usize]>,
}
impl std::ops::Index<usize> for Histogram {
type Output = usize;
fn index(&self, i: usize) -> &usize {
&self.bins[i]
}
}
impl std::ops::IndexMut<usize> for Histogram {
fn index_mut(&mut self, i: usize) -> &mut usize {
&mut self.bins[i]
}
}
impl AsRef<[usize]> for Histogram {
fn as_ref(&self) -> &[usize] {
self.bins.as_ref()
}
}
impl Histogram {
pub fn new(nbins: usize) -> Histogram {
Histogram {
total: 0,
bins: vec![0; nbins].into_boxed_slice(),
}
}
pub fn join(h: impl AsRef<[Histogram]>) -> Histogram {
let h = h.as_ref();
let mut hist = Histogram::new(h[0].len());
for i in h {
hist.total += i.total;
for (index, value) in i.bins() {
hist[index] += value
}
}
hist
}
pub fn add_value<T: Type>(&mut self, value: T) {
let x = value.to_norm() * (self.bins.len() - 1) as f64;
self.incr_bin(x.round() as usize)
}
pub fn incr_bin(&mut self, index: usize) {
self.bins[index] += 1;
self.total += 1;
}
pub fn bin(&self, index: usize) -> usize {
self.bins[index]
}
pub fn bins(&self) -> impl '_ + Iterator<Item = (usize, usize)> {
self.bins.iter().enumerate().map(|(a, b)| (a, *b))
}
pub fn len(&self) -> usize {
self.bins.len()
}
pub fn is_empty(&self) -> bool {
self.len() == 0
}
pub fn min_index(&self) -> usize {
let mut min = usize::MAX;
let mut index = 0;
for (i, n) in self.bins.iter().enumerate() {
if *n < min {
min = *n;
index = i;
}
}
index
}
pub fn max_index(&self) -> usize {
let mut max = 0;
let mut index = 0;
for (i, n) in self.bins.iter().enumerate() {
if *n > max {
max = *n;
index = i;
}
}
index
}
pub fn count(&self, v: usize) -> usize {
self.bins.iter().map(|bin| (*bin == v) as usize).sum()
}
pub fn distribution(&self) -> Vec<f64> {
let total: f64 = self.bins().map(|(_, x)| x as f64).sum();
self.bins().map(|(_, x)| x as f64 / total).collect()
}
pub fn sum(&self) -> usize {
self.total
}
}
#[cfg(test)]
mod tests {
use crate::*;
#[test]
fn test_histogram_basic() {
let image = Image::<f32, Rgb>::new((100, 100));
let hist = image.histogram(255);
for h in hist {
assert!(h.bins[0] == 100 * 100);
assert!(h.min_index() == 1);
assert!(h.max_index() == 0);
assert!(h.distribution()[0] == 1.0);
assert!(h.distribution().into_iter().skip(1).sum::<f64>() == 0.0);
}
}
}