count occurrences of number by column in pandas data frame

Question

I have a pandas data frame I want to count how often a number appears in a column for each column

     a   b   c   d   e
0    2   3   1   5   4
1    1   3            


        

Answer 1

You can do:

(df==1).sum()

df==1 gives:

       a      b      c      d      e
0  False  False   True  False  False
1   True  False  False  False  False
2   True  False  False  False  False
3  False  False   True  False  False
4  False  False   True  False  False

and the sum() treats False as 0 and True as 1.

Answer 2

This should do the trick

df1[df1 == 1].count()