python中list不能做索引

先看python中內置的list不能作為字典的key.

可將list或者ndarray轉化為tuple再做索引。

list不能進行hash：

import numpy as np
a1 = np.arange(3)
a2 = np.arange(3)
hash1 = hash(a1)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
TypeError: unhashable type: 'numpy.ndarray'

兩個ndarray轉為tuple后進行hash，所得的hash值是相同的

t1 = tuple(a1) t2 = tuple(a2)

hash1 = hash(t1)
hash2 = hash(t2)
print(hash1 == hash2)
True

 

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更新…

a1 = [1,2,3]
h1 = hash(str(a1))