I have the following df data frame in pandas:
weekday venta_total_cy 0 Viernes 5.430211e+09 1 Lunes 3.425554e+09 2 Sabado 6.833202e+09 3 Domingo 6.566466e+09 4 Jueves 2.748710e+09 5 Martes 3.328418e+09 6 Miercoles 3.136277e+09
What I want to do is to order the data frame by the following days’ order:
weekday Lunes Martes Miercoles Jueves Viernes Sabado Domingo
To do so, I used the following code:
df['weekday'] = pd.Categorical(df[['weekday']], categories=["Lunes", "Martes", "Miercoles", "Jueves", "Viernes", "Sabado", "Domingo"])
When I run the code, I get this error:
ValueError: Cannot setitem on a Categorical with a new category, set the categories first
I have not found enough documentation to resolve this. Can you help me? Thanks!
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Answer
df[['weekday']] returns a dataframe, which is incorrect. Convert the series column to categorical instead. Also, use the ordered=True argument to establish order in your categorical column.
categories = np.array(
['Lunes', 'Martes', 'Miercoles', 'Jueves', 'Viernes', 'Sabado', 'Domingo'])
df['weekday'] = pd.Categorical(
df['weekday'], categories=categories, ordered=True)
df.sort_values(by='weekday')
weekday venta_total_cy
1 Lunes 3.425554e+09
5 Martes 3.328418e+09
6 Miercoles 3.136277e+09
4 Jueves 2.748710e+09
0 Viernes 5.430211e+09
2 Sabado 6.833202e+09
3 Domingo 6.566466e+09