[英]Assign subset of values to pandas dataframe with MultiIndex
I have a DataFrame df
: 我有一个DataFrame
df
:
**Count**
**Environment** **Type**
**A** a 100
b 200
c 300
d 400
e 500
f 600
**B** a 1000
b 2000
c 3000
d 4000
e 5000
f 6000
The df.index
spits out the following index: df.index
吐出以下索引:
MultiIndex(levels=[['A', 'B'], ['a', 'b', 'c', 'd', 'e', 'f']],
labels=[[0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1],
[0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5]],
names=['A', 'B'])
I need to calculate the percentage of Counts per A and B. So I do: 我需要计算每个A和B的计数百分比。所以我这样做:
sums = df.groupby(level = 0).sum()
df.loc['A'] = df.loc['A'].apply(lambda x: x/sums.loc['A','Count'])
df.loc['B'] = df.loc['B'].apply(lambda x: x/sums.loc['B','Count'])
However, this results into all values being NaN
. 但是,这导致所有值均为
NaN
。
I suspect that the index of df.loc['B'].apply(lambda x: x/sums.loc['B','Count'])
is not the same as the index of df
, but it should be the same with the part of df
that I am selecting. 我怀疑
df.loc['B'].apply(lambda x: x/sums.loc['B','Count'])
的索引与df
的索引不同,但应该是与我选择的df
部分相同。
These by themselves 这些都是他们自己
df.loc['A'].apply(lambda x: x/sums.loc['A','Count'])
df.loc['B'].apply(lambda x: x/sums.loc['B','Count'])
have the values I need, so division works. 拥有我需要的价值,因此划分有效。 But, assignment does not.
但是,分配不是。
How do I assign the the result of the abovementioned expression to the part of the dataframe df
? 如何将上述表达式的结果分配给数据帧
df
的一部分 ?
Using div
to assign the value 使用
div
分配值
s=df.Count.div(df.Count.sum(level=0),axis=0,level=0)
df['per']=s
df
Out[1253]:
Count per
**Environment** **Type**
A a 100 0.047619
b 200 0.095238
c 300 0.142857
d 400 0.190476
e 500 0.238095
f 600 0.285714
B a 1000 0.047619
b 2000 0.095238
c 3000 0.142857
d 4000 0.190476
e 5000 0.238095
f 6000 0.285714
You can simply do df/sums
, no need for loop. 您可以简单地执行
df/sums
,而无需循环。
Since that you want to assign to a particular part of dataframe you can do it this way. 由于您要分配给数据框的特定部分,因此可以使用这种方法。 Keep the depth of computed df 1 level higher.
保持较高的df 1级深度。
df.loc['A',:] = df.loc['A',:,:].apply(lambda x: x/sums.loc['A','Count'])
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