Python以相反的字母顺序排列数据框列

Question

我目前的数据框列的顺序为df.columns = ['S1FF', 'S1Ipmax', 'S2POA',        ...       'M04Vpmax', 'M04elec_event', 'M04group', 'M04met_event', 'M04mode',       'M04validation_1min', 'M04validation_2min', 'M04S1T', 'M04S2T',       'M04datetime']  # Columns start with S1,S2, M01 to M24我想以相反的字母顺序对它们进行排序。我现在的代码是df = df.reindex(sorted(df.columns), axis=1)我现在的输出是df.columns = ['M01FF', 'M01Ipmax', 'M02POA',        ...       'S1FF', 'S1Ipmax', 'S2POA']但我的预期输出是反向字母顺序df.columns = ['S1FF', 'S1Ipmax', 'S2POA','M01FF', 'M01Ipmax', 'M02POA',        ...       'M23FF', 'M24Ipmax', 'M24POA']

Answer 1

key通过字符串的第一个值使用参数，这里S和Mwith reverse=True：

L = ['M01FF', 'M01Ipmax', 'M02POA', 'S1FF', 'S1Ipmax', 'S2POA']

df = pd.DataFrame(columns=L)

print (df)

Empty DataFrame

Columns: [M01FF, M01Ipmax, M02POA, S1FF, S1Ipmax, S2POA]

Index: []

df = df[sorted(df.columns, key=lambda x: x[0], reverse = True)]

print (df)

Empty DataFrame

Columns: [S1FF, S1Ipmax, S2POA, M01FF, M01Ipmax, M02POA]

Index: []

编辑：

import natsort as ns

s = ns.natsorted([x for x in df.columns if x[0] == 'S'])

m = ns.natsorted([x for x in df.columns if x[0] == 'M'])

df = df[s + m]