17 lines
605 B
Markdown
17 lines
605 B
Markdown
### difference_by
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Returns the difference between two list, after applying the provided function to each list element of both.
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Create a `set` by applying `fn` to each element in `b`, then use list comprehension in combination with fn on a to only keep values not contained in the previously created `set`.
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```python
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def difference_by(a, b, fn):
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b = set(map(fn, b))
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return [item for item in a if fn(item) not in b]
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```
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```python
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from math import floor
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difference_by([2.1, 1.2], [2.3, 3.4],floor) # [1.2]
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difference_by([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], lambda v : v['x']) # [ { x: 2 } ]
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``` |