Replace duplicated values with a blank string [closed]

Answer 1

I don't know if you literally want a blank string or NaN but I'm using NaN here, you can test if a column has duplicated values using duplicated and set these to your desired result, by the way you need to add an explanation of what your desired result means rather us guess:

In [128]:
df.loc[df['c1'].duplicated(), 'c1'] = np.NaN
df

Out[128]:
   c1   c2
0   3   10
1 NaN   30
2   1   20
3   2   15
4 NaN  100

The blank string version:

In [131]:
df.loc[df['c1'].duplicated(), 'c1'] = ''
df

Out[131]:
  c1   c2
0  3   10
1      30
2  1   20
3  2   15
4     100

EDIT

You updated your question so I've updated my answer:

In [143]:
df.loc[(df['a'].duplicated() & df['c1'].duplicated()), ['a','c1']] = ''
df

Out[143]:
        a c1   c2
0    Male  3   10
1              30
2    Male  1   20
3  Female  2   15
4             100