Concatenate cells into a string with separator pandas python

Question

Given the following:

df = pd.DataFrame({\'col1\' : [\"a\",\"b\"],
            \'col2\'  : [\"ab\",np.nan], \'col3\' : [\"w\",\"e\"]})

I would l

Answer 1

You can use dropna()

df['col4'] = df.apply(lambda row: '*'.join(row.dropna()), axis=1)

UPDATE:

Since, you need to convert numbers and special chars too, you can use astype(unicode)

In [37]: df = pd.DataFrame({'col1': ["a", "b"], 'col2': ["ab", np.nan], "col3": [3, u'\xf3']})

In [38]: df.apply(lambda row: '*'.join(row.dropna().astype(unicode)), axis=1)
Out[38]: 
0    a*ab*3
1       b*ó
dtype: object

In [39]: df['col4'] = df.apply(lambda row: '*'.join(row.dropna().astype(unicode)), axis=1)

In [40]: df
Out[40]: 
  col1 col2 col3    col4
0    a   ab    3  a*ab*3
1    b  NaN    ó     b*ó