使用列表中定义的多个条件过滤pandas数据帧

Question

我有pandas DataFrame,我想根据多个条件进行过滤.条件作为具有可变长度的列表传递.

以下是过滤DataFrame的基本代码:

>>>> conditions = ["a","b"]    
>>>> df1 = pd.DataFrame(["a","a","b","b","c"])
>>>> df1
   0
0  a
1  a
2  b
3  b
4  c
>>>> df2 = df1[(df1[0] == conditions[0]) | (df1[0] == conditions[1])]
>>>> df2
   0
0  a
1  a
2  b
3  b

如果我不知道传入的条件数量,是否有一种简单的方法可以检查所有条件？

谢谢

Answer 1

你可以用DataFrame.isin().

df2 = df1[df1[0].isin(conditions)]

Answer 2

NumPy ufuncs，如np.logical_or，有一个reduce方法：

import numpy as np
mask = np.logical_or.reduce([(df1[0] == cond) for cond in conditions])
df2 = df1[mask]