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

In [1556]: df.apply(lambda x: '*'.join(x.dropna().astype(str).values), axis=1)
Out[1556]: 
0    a*ab*w
1       b*e
2     3*4*�
3     ñ*ü*á
dtype: object