Replace duplicate values across columns in Pandas

Question

I have a simple dataframe as such:

df = [    {\'col1\' : \'A\', \'col2\': \'B\', \'col3\':   \'C\', \'col4\':\'0\'},
          {\'col1\' : \'M\', \'col2\':         


        

Answer 1

You can use the duplicated method to return a boolean indexer of whether elements are duplicates or not:

In [214]: pd.Series(['M', '0', 'M', '0']).duplicated()
Out[214]:
0    False
1    False
2     True
3     True
dtype: bool

Then you could create a mask by mapping this across the rows of your dataframe, and using where to perform your substitution:

is_duplicate = df.apply(pd.Series.duplicated, axis=1)
df.where(~is_duplicate, 0)

  col1 col2 col3 col4
0    A    B    C    0
1    M    0    0    0
2    B    0    0    0
3    X    0    Y    0