sort a dataframe according to a column pandas code example

Example 1: df sort values

>>> df.sort_values(by=['col1'], ascending = False)
    col1 col2 col3
0   A    2    0
1   A    1    1
2   B    9    9
5   C    4    3
4   D    7    2
3   NaN  8    4

Example 2: sort columns dataframe

df = df.reindex(sorted(df.columns), axis=1)