how to apply a function to multiple columns in pandas dataframe
>>> print df
A B C
0 -1 0 0
1 -4 3 -1
2 -1 0 2
3 0 3 2
4 1 -1 0
>>> print df.applymap(lambda x: x>1)
A B C
0 False False False
1 False True False
2 False False True
3 False True True
4 False False False