19 lines
690 B
Markdown
19 lines
690 B
Markdown
---
|
|
title: symmetric_difference_by
|
|
tags: list,function,intermediate
|
|
---
|
|
|
|
Returns the symmetric difference between two lists, after applying the provided function to each list element of both.
|
|
|
|
Create a `set` by applying `fn` to each element in every list, then use list comprehension in combination with `fn` on each one to only keep values not contained in the previously created set of the other.
|
|
|
|
```py
|
|
def symmetric_difference_by(a, b, fn):
|
|
_a, _b = set(map(fn, a)), set(map(fn, b))
|
|
return [item for item in a if fn(item) not in _b] + [item for item in b if fn(item) not in _a]
|
|
```
|
|
|
|
```py
|
|
from math import floor
|
|
symmetric_difference_by([2.1, 1.2], [2.3, 3.4],floor) # [1.2, 3.4]
|
|
``` |