pandas 在一定水平上随机排列 [英] Pandas shuffle rows at a certain level
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问题描述
我在行上使用MultiIndex
的熊猫DataFrame
:
index = pandas.MultiIndex.from_tuples(list(itertools.product(range(3), range(3))))
df = pandas.DataFrame(numpy.random.randn(9,3), index=index, columns=['A', 'B', 'C'])
A B C
0 0 2.400417 0.698638 1.231540
1 -0.023154 -2.110450 0.774964
2 -1.282392 -0.062794 1.471655
1 0 -1.081853 0.261876 -1.771075
1 -2.013747 -0.377957 -0.393802
2 1.711172 -0.552468 1.018727
2 0 0.155821 -0.222691 0.496586
1 0.563638 -0.756709 1.050212
2 -1.446159 -0.891549 0.256695
我想在索引的第一层改组此DataFrame,所以可能的结果是:
I would like to shuffle this DataFrame on the first level of the index, so a possible result would be:
A B C
1 0 -1.081853 0.261876 -1.771075
1 -2.013747 -0.377957 -0.393802
2 1.711172 -0.552468 1.018727
0 0 2.400417 0.698638 1.231540
1 -0.023154 -2.110450 0.774964
2 -1.282392 -0.062794 1.471655
2 0 0.155821 -0.222691 0.496586
1 0.563638 -0.756709 1.050212
2 -1.446159 -0.891549 0.256695
推荐答案
通过传递与所需顺序匹配的元组重新排序的数组时,reindex
方法可以实现此目的.此时,可以最适合您的问题进行重新排序.例如:
The reindex
method can accomplish this when passed a reordered array of tuples matching the desired order. At which point, reordering can be done as best fits your problem. For example:
In [38]: df
Out[38]:
A B C
0 0 -1.725337 0.111493 0.178294
1 -1.809003 -0.614219 -0.931909
2 0.621427 -0.186233 0.254727
1 0 -1.322863 1.242415 1.375579
1 0.249738 -1.280204 0.356491
2 -0.743671 0.325841 -0.167772
2 0 -0.070937 0.401172 -1.790801
1 1.433794 2.257198 1.848435
2 -1.021557 -1.054363 -1.485536
In [39]: neworder = [1, 0, 2]
In [41]: newindex = sorted(df.index, key=lambda x: neworder.index(x[0]))
In [42]: newindex
Out[42]:
[(1L, 0L),
(1L, 1L),
(1L, 2L),
(0L, 0L),
(0L, 1L),
(0L, 2L),
(2L, 0L),
(2L, 1L),
(2L, 2L)]
In [43]: df.reindex(newindex)
Out[43]:
A B C
1 0 -1.322863 1.242415 1.375579
1 0.249738 -1.280204 0.356491
2 -0.743671 0.325841 -0.167772
0 0 -1.725337 0.111493 0.178294
1 -1.809003 -0.614219 -0.931909
2 0.621427 -0.186233 0.254727
2 0 -0.070937 0.401172 -1.790801
1 1.433794 2.257198 1.848435
2 -1.021557 -1.054363 -1.485536
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