> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/e/entropy.md).

# Entropy

```ruby
func entropy(s) {
  var counts = Hash.new;
  s.each { |c| counts{c} := 0 ++ };
  var len = s.len;
  [0, counts.values.map {|count|
    var freq = count/len; freq * freq.log2 }...
  ]«-»;
}
 
say entropy("1223334444");
```

#### Output:

```
1.846439344671015493434197746305045223237
```