I have the DataFrame

df = pd.DataFrame({'colA':['?',2,3,4,'?'],'colB':[1,2,'?',3,4],'colC':['?',2,3,4,5]
})

I would like to get the count the the number of '?' in each column and return the following output -

colA - 2
colB - 1
colC - 1

Is there a way to return this output at once. Right now the only way I know how to do it is write a for loop for each column.

looks like the simple way is

df[df == '?'].count()

the result is

colA    2
colB    1
colC    1
dtype: int64

where df[df == '?'] give us DataFrame with ? and Nan

  colA colB colC
0    ?  NaN    ?
1  NaN  NaN  NaN
2  NaN    ?  NaN
3  NaN  NaN  NaN
4    ?  NaN  NaN

and the count non-NA cells for each column.

Please, look on the other solutions: good readable and the most faster