Pandas (45)

How to change the order of columns of a dataframe?

# Input
df = pd.DataFrame(np.arange(20).reshape(-1, 5), columns=list('abcde'))

# 1
df[list('cbade')]

# 2 - No hard coding
def switch_columns(df, col1=None, col2=None):
    colnames = df.columns.tolist()
    i1, i2 = colnames.index(col1), colnames.index(col2)
    colnames[i2], colnames[i1] = colnames[i1], colnames[i2]
    return df[colnames]

df1 = switch_columns(df, 'a', 'c')

# 3
df[sorted(df.columns)]
# or
df.sort_index(axis=1, ascending=False, inplace=True)