python - Pandas - 反转和分配列名称不起作用

Question

我有一个包含 6000 列的 df，其中一个子集(1500 列)的列名称颠倒错误。

我可以像这样提取子集:

orderbook.loc[:,'ask_price_1500':'ask_price_1'].columns

并获取列:

Index(['ask_price_1500', 'ask_price_1499', 'ask_price_1498', 'ask_price_1497',
       'ask_price_1496', 'ask_price_1495', 'ask_price_1494', 'ask_price_1493',
       'ask_price_1492', 'ask_price_1491',
       ...
       'ask_price_10', 'ask_price_9', 'ask_price_8', 'ask_price_7',
       'ask_price_6', 'ask_price_5', 'ask_price_4', 'ask_price_3',
       'ask_price_2', 'ask_price_1'],
      dtype='object', length=1500)

现在反转列非常容易，我只需添加 [::-1] 即可获得新顺序。

Index(['ask_price_1', 'ask_price_2', 'ask_price_3', 'ask_price_4',
       'ask_price_5', 'ask_price_6', 'ask_price_7', 'ask_price_8',
       'ask_price_9', 'ask_price_10',
       ...
       'ask_price_1491', 'ask_price_1492', 'ask_price_1493', 'ask_price_1494',
       'ask_price_1495', 'ask_price_1496', 'ask_price_1497', 'ask_price_1498',
       'ask_price_1499', 'ask_price_1500'],
      dtype='object', length=1500)

但是，当尝试分配这些反向列时

orderbook.loc[:,'ask_price_1500':'ask_price_1'].columns = orderbook.loc[:,'ask_price_1500':'ask_price_1'].columns[::-1]

它没有任何效果，列名也不会改变。

感谢任何帮助 - 谢谢。

Answer 1

做一些子列表反转和重新分配:

v = orderbook.columns.tolist()
# The index that comes first.
i = orderbook.columns.get_loc('ask_price_1500')
# The index that comes second.
j = orderbook.columns.get_loc('ask_price_1')
# Reverse list subslice.
v[i:j+1] = v[j:i-1:-1]
# Assign the result back to the DataFrame.
df.columns = v