24 lines
614 B
Markdown
24 lines
614 B
Markdown
---
|
|
title: group_by
|
|
tags: list,object,beginner
|
|
---
|
|
|
|
Groups the elements of a list based on the given function.
|
|
|
|
Use `list()` in combination with `map()` and `fn` to map the values of the list to the keys of an object.
|
|
Use list comprehension to map each element to the appropriate `key`.
|
|
|
|
```py
|
|
def group_by(lst, fn):
|
|
groups = {}
|
|
for key in list(map(fn,lst)):
|
|
groups[key] = [item for item in lst if fn(item) == key]
|
|
return groups
|
|
```
|
|
|
|
```py
|
|
import math
|
|
group_by([6.1, 4.2, 6.3], math.floor); # {4: [4.2], 6: [6.1, 6.3]}
|
|
group_by(['one', 'two', 'three'], 'length'); # {3: ['one', 'two'], 5: ['three']}
|
|
```
|