python - 返回一个 bool 数据框

Question

我想用 bool 值创建一个 DataFrame，其中 np.nan == False 和任何正实数值 == True。

import numpy as np
import pandas as pd
DF = pd.DataFrame({'a':[1,2,3,4,np.nan],'b':[np.nan,np.nan,np.nan,5,np.nan]})

DF.apply(bool) # Does not work
DF.where(DF.isnull() == False) # Does not work
DF[DF.isnull() == False] # Does not work

Answer 1

很奇怪，但它看起来像 - np.isnan(df) 以压倒性优势胜过 pd.notnull(df):

In [1]: import pandas as pd

In [2]: import numpy as np

In [3]: df = pd.DataFrame({'a':[1,2,3,4,np.nan],'b':[np.nan,np.nan,np.nan,5,np.nan]})


In [4]: - np.isnan(df)
Out[4]: 
       a      b
0   True  False
1   True  False
2   True  False
3   True   True
4  False  False

In [5]: %timeit - np.isnan(df)
10000 loops, best of 3: 159 us per loop

In [6]: %timeit pd.notnull(df)
1000 loops, best of 3: 1.22 ms per loop