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Faster matrix construction

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This commit is contained in:
Andrew 2026-06-04 08:18:28 +12:00
parent 0466546981
commit 70fddcd6d4
1 changed files with 11 additions and 4 deletions
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15
src/reduction/palette.rs
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@ -267,24 +267,31 @@ fn co_occurrence_matrix(num_colors: usize, png: &PngImage) -> Vec<Vec<u32>> {
for line in png.scan_lines(false) {
for i in 0..line.data.len() {
let val = line.data[i] as usize;
if val > num_colors {
if val >= num_colors {
continue;
}
if let Some(prev_val) = prev_val.replace(val) {
matrix[prev_val][val] += 1;
matrix[val][prev_val] += 1;
}
if let Some(prev) = &prev {
let prev_val = prev.data[i] as usize;
if prev_val > num_colors {
if prev_val >= num_colors {
continue;
}
matrix[prev_val][val] += 1;
matrix[val][prev_val] += 1;
}
}
prev = Some(line);
}
// Make the matrix symmetrical - this is faster to do afterward than maintaining symmetry during counting
#[allow(clippy::needless_range_loop)]
for i in 0..num_colors {
for j in 0..num_colors {
matrix[j][i] += matrix[i][j];
matrix[i][j] = matrix[j][i];
}
}
matrix
}