https://ja.stackoverflow.com/q/36555/19110

pandas.DataFrame.log

Python 3.6.0 |Anaconda 4.3.1 (64-bit)| (default, Dec 23 2016, 12:22:00) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy as np
>>> import pandas as pd
>>> test = pd.DataFrame(np.random.choice([0.0, 100.0], size=(4, 4)))
>>> test
       0      1      2      3
0    0.0    0.0  100.0  100.0
1  100.0  100.0    0.0  100.0
2    0.0  100.0  100.0  100.0
3  100.0  100.0  100.0  100.0
>>> train = pd.DataFrame(np.random.rand(4, 4))
>>> train
          0         1         2         3
0  0.435729  0.543282  0.911146  0.394409
1  0.693686  0.955173  0.729586  0.808441
2  0.155083  0.327989  0.405951  0.854187
3  0.623706  0.349019  0.286164  0.626817
>>> test = test.where(test == 0, train)
>>> test
          0         1         2         3
0  0.000000  0.000000  0.911146  0.394409
1  0.693686  0.955173  0.000000  0.808441
2  0.000000  0.327989  0.405951  0.854187
3  0.623706  0.349019  0.286164  0.626817
>>>