6/6 df

import pandas as pd
df = pd.DataFrame({'col01':[1, 5, 9, 13, 17],
'col02':[2, 6, 10, 14, 18],
'col03':[7, 3, 19, 11, 15],
'col04':[4, 8, 12, 16, 20]},
index=['idx01', 'idx02', 'idx03', 'idx04', 'idx05'])
df.sort_values(by = "idx03" , axis = 1)

##sort_valuesメソッドを使用し、引数axisに1
idx03のcol3が[7, 3, 19, 11, 15]→[3, 7, 11, 15, 19]