当列包含“列表”而不是“元组”时，比较运算符“==”未按预期工作`

Question

import pandas as pd
import numpy as np

df = pd.DataFrame({'Li':[[1,2],[5,6],[8,9]],'Tu':[(1,2),(5,6),(8,9)]}
df
       Li      Tu
0  [1, 2]  (1, 2)
1  [5, 6]  (5, 6)
2  [8, 9]  (8, 9)

为Tuple工作罚款

df.Tu == (1,2)
0     True
1    False
2    False
Name: Tu, dtype: bool

当其List时，它给出值错误

df.Li == [1,2]

ValueError: Lengths must match to compare

Answer 1

问题是list是不可散列的，因此有必要比较tuples：

print (df.Li.map(tuple) == (1,2))
0     True
1    False
2    False
Name: Li, dtype: bool

或在列表理解中：

mask = [tuple(x) == (1,2) for x in df.Li]
#alternative
mask = [x == [1,2] for x in df.Li]
print (mask)
[True, False, False]

如果所有列表的长度相同：

mask = (np.array(df.Li.tolist()) == [1,2]).all(axis=1)
print (mask)
[ True False False]