python - get dataframe row count based on conditions

Question

I want to get the count of dataframe rows based on conditional selection. I tried the following code.

print df[(df.IP == head.idxmax()) & (df.Method == 'HEAD') & (df.Referrer == '"-"')].count()

output:

IP          57
Time        57
Method      57
Resource    57
Status      57
Bytes       57
Referrer    57
Agent       57
dtype: int64

The output shows the count for each an every column in the dataframe. Instead I need to get a single count where all of the above conditions satisfied? How to do this? If you need more explanation about my dataframe please let me know.

Answer 1

You are asking for the condition where all the conditions are true, so len of the frame is the answer, unless I misunderstand what you are asking

In [17]: df = DataFrame(randn(20,4),columns=list('ABCD'))

In [18]: df[(df['A']>0) & (df['B']>0) & (df['C']>0)]
Out[18]: 
           A         B         C         D
12  0.491683  0.137766  0.859753 -1.041487
13  0.376200  0.575667  1.534179  1.247358
14  0.428739  1.539973  1.057848 -1.254489

In [19]: df[(df['A']>0) & (df['B']>0) & (df['C']>0)].count()
Out[19]: 
A    3
B    3
C    3
D    3
dtype: int64

In [20]: len(df[(df['A']>0) & (df['B']>0) & (df['C']>0)])
Out[20]: 3