how to sort in pandas
// Single sort >>> df.sort_values(by=['col1'],ascending=False) // ascending => [False(reverse order) & True(default)] // Multiple Sort >>> df.sort_values(by=['col1','col2'],ascending=[True,False]) // with apply() >>> df[['col1','col2']].apply(sorted,axis=1) // axis = [1 & 0], 1 = 'columns', 0 = 'index'