python - 用 NaN 替换重复的列表元素

Question

我想用 NaN 替换数组中所有重复的元素。例如:

a = [1, 1, 2, 3, 1, 8, 5, 6, 7, 5, 5]

目标:

a = [NaN, NaN, 2, 3, NaN, 8, NaN, 6, 7, NaN, NaN]

Answer 1

您可以使用collections.Counter计算 a 中每个元素的所有实例，然后根据计数创建一个新的 a:

from collections import Counter

a = [1, 1, 2, 3, 1, 8, 5, 6, 7, 5, 5]
histogram = Counter(a)

a = [n if histogram[n]<=1 else None for n in a]
print(a)