Pandas DataFrame, How do I remove all columns and rows that sum to 0

Question

I have a dataFrame with rows and columns that sum to 0.

    A   B   C    D
0   1   1   0    1
1   0   0   0    0 
2   1   0   0    1
3   0   1   0    0  
4   1   1   0    1

The end result should be

    A   B    D
0   1   1    1
2   1   0    1
3   0   1    0  
4   1   1    1

Notice the rows and columns that only had zeros have been removed.

score 31 · Accepted Answer · answered May 09 '14 at 20:05

31

df.loc[row_indexer, column_indexer] allows you to select rows and columns using boolean masks:

In [88]: df.loc[(df.sum(axis=1) != 0), (df.sum(axis=0) != 0)]
Out[88]: 
   A  B  D
0  1  1  1
2  1  0  1
3  0  1  0
4  1  1  1

[4 rows x 3 columns]

df.sum(axis=1) != 0 is True if and only if the row does not sum to 0.

df.sum(axis=0) != 0 is True if and only if the column does not sum to 0.

answered May 09 '14 at 20:05

unutbu

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4

Of all the rare times it is appropriate to use the term "iff" and you missed it! – Cory Kramer May 09 '14 at 20:09
2

@Cyber: It's the Zen of Python: simple is better than complex; readability counts :) – unutbu May 09 '14 at 20:10
6

And if you want to select all rows but only columns that don't sum to zero: `df.loc[:, (df.sum(axis=0) != 0)]` – RobertF Aug 06 '19 at 15:56

score 7 · Answer 2 · edited May 23 '17 at 12:25

7

building on Drop rows with all zeros in pandas data frame to avoid using the sum()

df = pd.DataFrame({'A': [1,0,1,0,1],
                   'B': [1,0,0,1,1],
                   'C': [0,0,0,0,0],
                   'D': [1,0,1,0,1]})

df.loc[(df!=0).any(1), (df!=0).any(0)]

   A  B  D
0  1  1  1
2  1  0  1
3  0  1  0
4  1  1  1

edited May 23 '17 at 12:25

Community

1
1

answered Aug 31 '16 at 00:12

Ziggy Eunicien

2,858
1
23
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score 0 · Answer 3 · answered Feb 20 '16 at 07:29

This is my way to do it:

import pandas as pd 
hl = []
df =  pd.read_csv("my.csv")
l = list(df.columns.values)
for l in l:
    if sum(df[l]) != 0:
        hl.append(l)
df2 = df[hl]

to write reduced_Data:

df2.to_csv("my_reduced_data.csv")

It will only check columns but ignore Rows

Pandas DataFrame, How do I remove all columns and rows that sum to 0

3 Answers3

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