I want to delete a line in python

Question

I want to delete a line that the column[3] is not 0 in python.

#prepare
from numpy import nan as NA
from pandas import Series,DataFrame

data=DataFrame([[1.,6.5,3.,0],[1.,NA,NA,0.],[NA,NA,NA,1],[NA,6.5,3.,7.]])
data
     0    1    2    3
0  1.0  6.5  3.0  0.0
1  1.0  NaN  NaN  0.0
2  NaN  NaN  NaN  1.0
3  NaN  6.5  3.0  7.0

I performed the following code,but it didn't work well.

Third=data[3]
for i in range(len(data.index)):
if not Third[i] is 0:
    drop_idx=[i]
    data.drop(drop_idx,axis=0)

Result

     0    1    2    3
1  1.0  NaN  NaN  0.0
2  NaN  NaN  NaN  1.0
3  NaN  6.5  3.0  7.0
     0    1    2    3
0  1.0  6.5  3.0  0.0
2  NaN  NaN  NaN  1.0
3  NaN  6.5  3.0  7.0
     0    1    2    3
0  1.0  6.5  3.0  0.0
1  1.0  NaN  NaN  0.0
3  NaN  6.5  3.0  7.0
     0    1    2    3
0  1.0  6.5  3.0  0.0
1  1.0  NaN  NaN  0.0
2  NaN  NaN  NaN  1.0

I would like to know how to get the following result.Could you tell me where wrong?

     0    1    2    3
0  1.0  6.5  3.0  0.0
1  1.0  NaN  NaN  0.0

Answer 1

This will do the job:

import pandas as pd
data=pd.DataFrame([[1.,6.5,3.,0],[1.,None,None,0.],[None,None,None,1],[None,6.5,3.,7.]])
data=data[data[3]==0]

Then data is

    0   1   2   3
0   1.0 6.5 3.0 0.0
1   1.0 NaN NaN 0.0

You could also do that inplace as follows:

import pandas as pd
data=pd.DataFrame([[1.,6.5,3.,0],[1.,None,None,0.],[None,None,None,1],[None,6.5,3.,7.]])
data.drop(data[data[3]!=0].index,inplace=True)