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Center skewed parameters around the skew center

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It's a bit awkward and you can completely lose some parts of the range
if you don't do this.
This commit is contained in:
Robbert van der Helm 2022-02-02 00:05:50 +01:00
parent 1202b2b9d6
commit 63e4a54d7c
1 changed files with 19 additions and 23 deletions
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42
src/param/range.rs
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@ -26,7 +26,9 @@ pub enum Range<T> {
/// for a more intuitively way to calculate the skew factor where positive values skew the range
/// towards the end while negative values skew the range toward the start.
Skewed { min: T, max: T, factor: f32 },
/// The same as [Range::Skewed], but with the skewing happening from a central point.
/// The same as [Range::Skewed], but with the skewing happening from a central point. This
/// central point is rescaled to be at 50% of the parameter's range for convenience of use. Git
/// blame this comment to find a version that doesn't do this.
SymmetricalSkewed {
min: T,
max: T,
@ -87,8 +89,7 @@ impl NormalizebleRange<f32> for Range<f32> {
// unnormalized and scaled back to the original [center_proportion, 1] range
let scaled_proportion = (unscaled_proportion - center_proportion)
* (1.0 - center_proportion).recip();
(scaled_proportion.powf(*factor) * (1.0 - center_proportion))
+ center_proportion
(scaled_proportion.powf(*factor) * 0.5) + 0.5
} else {
// The part below the center gets scaled, inverted (so the range is [0, 1] where
// 0 corresponds to the center proportion and 1 corresponds to the orignal
@ -96,7 +97,7 @@ impl NormalizebleRange<f32> for Range<f32> {
// original range
let inverted_scaled_proportion =
(center_proportion - unscaled_proportion) * (center_proportion).recip();
(1.0 - inverted_scaled_proportion.powf(*factor)) * (center_proportion)
(1.0 - inverted_scaled_proportion.powf(*factor)) * 0.5
}
}
}
@ -118,15 +119,13 @@ impl NormalizebleRange<f32> for Range<f32> {
} => {
// Reconstructing the subranges works the same as with the normal skewed ranges
let center_proportion = (center - min) / (max - min);
let skewed_proportion = if normalized > center_proportion {
let scaled_proportion =
(normalized - center_proportion) * (1.0 - center_proportion).recip();
let skewed_proportion = if normalized > 0.5 {
let scaled_proportion = (normalized - 0.5) * 2.0;
(scaled_proportion.powf(factor.recip()) * (1.0 - center_proportion))
+ center_proportion
} else {
let inverted_scaled_proportion =
(center_proportion - normalized) * (center_proportion).recip();
(1.0 - inverted_scaled_proportion.powf(factor.recip())) * (center_proportion)
let inverted_scaled_proportion = (0.5 - normalized) * 2.0;
(1.0 - inverted_scaled_proportion.powf(factor.recip())) * center_proportion
};
(skewed_proportion * (max - min)) + min
@ -154,12 +153,11 @@ impl NormalizebleRange<i32> for Range<i32> {
if unscaled_proportion > center_proportion {
let scaled_proportion = (unscaled_proportion - center_proportion)
* (1.0 - center_proportion).recip();
(scaled_proportion.powf(*factor) * (1.0 - center_proportion))
+ center_proportion
(scaled_proportion.powf(*factor) * 0.5) + 0.5
} else {
let inverted_scaled_proportion =
(center_proportion - unscaled_proportion) * (center_proportion).recip();
(1.0 - inverted_scaled_proportion.powf(*factor)) * (center_proportion)
(1.0 - inverted_scaled_proportion.powf(*factor)) * 0.5
}
}
}
@ -180,15 +178,13 @@ impl NormalizebleRange<i32> for Range<i32> {
center,
} => {
let center_proportion = (center - min) as f32 / (max - min) as f32;
let skewed_proportion = if normalized > center_proportion {
let scaled_proportion =
(normalized - center_proportion) * (1.0 - center_proportion).recip();
let skewed_proportion = if normalized > 0.5 {
let scaled_proportion = (normalized - 0.5) * 2.0;
(scaled_proportion.powf(factor.recip()) * (1.0 - center_proportion))
+ center_proportion
} else {
let inverted_scaled_proportion =
(center_proportion - normalized) * (center_proportion).recip();
(1.0 - inverted_scaled_proportion.powf(factor.recip())) * (center_proportion)
let inverted_scaled_proportion = (0.5 - normalized) * 2.0;
(1.0 - inverted_scaled_proportion.powf(factor.recip())) * center_proportion
};
(skewed_proportion * (max - min) as f32).round() as i32 + min
@ -361,25 +357,25 @@ mod tests {
#[test]
fn range_normalize_float() {
let range = make_symmetrical_skewed_float_range(Range::skew_factor(-2.0));
assert_eq!(range.normalize(17.5), 0.9277015);
assert_eq!(range.normalize(17.5), 0.951801);
}
#[test]
fn range_normalize_int() {
let range = make_symmetrical_skewed_int_range(Range::skew_factor(-2.0));
assert_eq!(range.normalize(-5), 0.09411134);
assert_eq!(range.normalize(-5), 0.13444477);
}
#[test]
fn range_unnormalize_float() {
let range = make_symmetrical_skewed_float_range(Range::skew_factor(-2.0));
assert_eq!(range.unnormalize(0.9277015), 17.5);
assert_eq!(range.unnormalize(0.951801), 17.5);
}
#[test]
fn range_unnormalize_int() {
let range = make_symmetrical_skewed_int_range(Range::skew_factor(-2.0));
assert_eq!(range.unnormalize(0.09411134), -5);
assert_eq!(range.unnormalize(0.13444477), -5);
}
}
}