[FIXED] Python Pandas: How to unique strings in a column

Issue

I have a table like this:

col1 col2
ben US-US-Uk
Man Uk-NL-DE
bee CA-CO-MX-MX

how can I unique the values in col 2, which means have a table like this?

col1 col2
ben US-Uk
Man Uk-NL-DE
bee CA-CO-MX

I have tried this :

a.cc.str.split('-').unique()

but get the following error:

TypeError: unhashable type: 'list'

Does anybody know how to do this?

Solution

You can use apply to call a lambda function that splits the string and then joins on the unique values:

In [10]:

df['col2'] = df['col2'].apply(lambda x: '-'.join(set(x.split('-'))))
df
Out[10]:
  col1      col2
0  ben     Uk-US
1  Man  Uk-NL-DE
2  bee  CA-CO-MX

Another method:

In [22]:

df['col2'].str.split('-').apply(lambda x: '-'.join(set(x)))

Out[22]:
0       Uk-US
1    Uk-NL-DE
2    CA-CO-MX
Name: col2, dtype: object

timings

In [24]:

%timeit df['col2'].str.split('-').apply(lambda x: '-'.join(set(x)))
%timeit df['col2'] = df['col2'].apply(lambda x: '-'.join(set(x.split('-'))))
1000 loops, best of 3: 418 µs per loop
1000 loops, best of 3: 246 µs per loop

Answered By - EdChum