How do I merge the unique values in columns A
and B
from df
into list
?
id A B
1 x k
2 y x
3 x l
4 x k
This is what I am trying to achieve:
list = ['x', 'y', 'k', 'l']
Failed attempt:
list = df['A'].unique().tolist()
list.append(df['B'].unique())
The output:
['x', 'y', ['x', 'k', 'l']]
Use np.ravel
and np.unique
:
# Global unique
>>> np.unique(np.ravel(df[['A', 'B']])).tolist()
['k', 'l', 'x', 'y']
# Per column unique
>>> df['A'].unique().tolist() + df['B'].unique().tolist()
['x', 'y', 'k', 'x', 'l']