24 lines
620 B
Markdown
24 lines
620 B
Markdown
---
|
|
title: frequencies
|
|
tags: list,intermediate
|
|
---
|
|
|
|
Returns a dictionary with the unique values of a list as keys and their frequencies as the values.
|
|
|
|
- Use `collections.defaultdict()` to store the frequencies of each unique element.
|
|
- Use `dict()` to return a dictionary with the unique elements of the list as keys and their frequencies as the values.
|
|
|
|
```py
|
|
from collections import defaultdict
|
|
|
|
def frequencies(lst):
|
|
freq = defaultdict(int)
|
|
for val in lst:
|
|
freq[val] += 1
|
|
return dict(freq)
|
|
```
|
|
|
|
```py
|
|
frequencies(['a', 'b', 'a', 'c', 'a', 'a', 'b']) # { 'a': 4, 'b': 2, 'c': 1 }
|
|
```
|