30秒学会 Python 片段 – List difference based on function

Returns the difference between two lists, after applying the provided function to each list element of both.

• Create a set, using map() to apply fn to each element in b.
• Use a list comprehension in combination with fn on a to only keep values not contained in the previously created set, _b.

代码实现

def difference_by(a, b, fn):
  _b = set(map(fn, b))
  return [item for item in a if fn(item) not in _b]

使用样例

from math import floor

difference_by([2.1, 1.2], [2.3, 3.4], floor) # [1.2]
difference_by([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], lambda v : v['x'])
# [ { x: 2 } ]

翻译自：https://www.30secondsofcode.org/python/s/difference-by