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September Morn Update

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This commit is contained in:
Ingy döt Net 2019-09-12 10:33:56 -07:00
parent 4e2d22a71d
commit aac6731f2c
6856 changed files with 141342 additions and 21127 deletions
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24
Task/Entropy/Rust/entropy.rust
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@ -1,20 +1,20 @@
fn entropy(s: &[u8]) -> f32 {
let mut entropy: f32 = 0.0;
let mut histogram = [0; 256];
let mut histogram = [0u64; 256];
for i in 0..s.len() {
histogram.get_mut(s[i] as usize).map(|v| *v += 1);
for &b in s {
histogram[b as usize] += 1;
}
for i in 0..256 {
if histogram[i] > 0 {
let ratio = (histogram[i] as f32 / s.len() as f32) as f32;
entropy -= (ratio * ratio.log2()) as f32;
}
}
entropy
histogram
.iter()
.cloned()
.filter(|&h| h != 0)
.map(|h| h as f32 / s.len() as f32)
.map(|ratio| -ratio * ratio.log2())
.sum()
}
fn main() {
let arg = std::env::args().nth(1).expect("Need a string.");
println!("Entropy of {} is {}.", arg, entropy(&arg.bytes().collect::<Vec<_>>()));
println!("Entropy of {} is {}.", arg, entropy(arg.as_bytes()));
}