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[英]Sorting Pandas MultiIndex by the last value of level 0 index
[英]Custom sorting of the level 1 index of a multiindex Pandas DataFrame according to the level 0 index
我有一個多索引DataFrame, df
:
arrays = [['bar', 'bar', 'baz', 'baz', 'baz', 'baz', 'foo', 'foo'],
['one', 'two', 'one', 'two', 'three', 'four', 'one', 'two']]
df = pd.DataFrame(np.ones([8, 4]), index=arrays)
看起來像:
0 1 2 3
bar one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
baz one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
three 1.0 1.0 1.0 1.0
four 1.0 1.0 1.0 1.0
foo one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
我現在需要將' baz
'子級別排序為新的順序,以創建看起來像df_end
東西:
arrays_end = [['bar', 'bar', 'baz', 'baz', 'baz', 'baz', 'foo', 'foo'],
['one', 'two', 'two', 'four', 'three', 'one', 'one', 'two']]
df_end = pd.DataFrame(np.ones([8, 4]), index=arrays_end)
看起來像:
0 1 2 3
bar one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
baz two 1.0 1.0 1.0 1.0
four 1.0 1.0 1.0 1.0
three 1.0 1.0 1.0 1.0
one 1.0 1.0 1.0 1.0
foo one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
我以為我可以重新索引baz
行:
new_index = ['two','four','three','one']
df.loc['baz'].reindex(new_index)
這使:
0 1 2 3
two 1.0 1.0 1.0 1.0
four 1.0 1.0 1.0 1.0
three 1.0 1.0 1.0 1.0
one 1.0 1.0 1.0 1.0
...並將這些值插回到原始DataFrame中:
df.loc['baz'] = df.loc['baz'].reindex(new_index)
但結果是:
0 1 2 3
bar one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
baz one NaN NaN NaN NaN
two NaN NaN NaN NaN
three NaN NaN NaN NaN
four NaN NaN NaN NaN
foo one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
這不是我想要的! 所以我的問題是如何使用new_index
重新排序baz
索引中的行。 任何建議將不勝感激。
編輯:(以適合所需的布局)
arrays = [['bar', 'bar', 'baz', 'baz', 'baz', 'baz', 'foo', 'foo'],
['one', 'two', 'one', 'two', 'three', 'four', 'one', 'two']]
df = pd.DataFrame(np.arange(32).reshape([8, 4]), index=arrays)
new_baz_index = [('baz', i) for i in ['two','four','three','one']]
index = df.index.values.copy()
index[df.index.get_loc('baz')] = new_baz_index
df.reindex(index)
df.index.get_loc('baz')
將獲取baz
零件的位置作為切片對象,我們只替換那里的零件。
更新:-)
pd.concat([df[df.index.get_level_values(level=0)!='baz'],df.reindex(list(zip(['baz']*4,['two','four','three','one'])))])
Out[1156]:
0 1 2 3
bar one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
foo one 1.0 1.0 1.0 1.0
two 1.0 1.0 1.0 1.0
baz two 1.0 1.0 1.0 1.0
four 1.0 1.0 1.0 1.0
three 1.0 1.0 1.0 1.0
one 1.0 1.0 1.0 1.0
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