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use set()

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Victor Schmidt
2018-10-08 17:56:23 +02:00
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snippets/difference.md
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Returns the difference between two iterables. Returns the difference between two iterables.
Use list comprehension to only keep values not contained in `b` Use list comprehension to only keep values not contained in `b`. Use set to test `in` in `O(1)` time.
```python ```python
def difference(a, b): def difference(a, b):
return [item for item in a if item not in b] _b = set(b)
return [item for item in a if item not in _b]
``` ```
``` python ``` python
difference([1, 2, 3], [1, 2, 4]) # [3] difference([1, 2, 3], [1, 2, 4]) # [3]