pandas :从数据透视表中的另一列中减去一列
问题描述
我想从数据透视表中的另一列中减去一列.'diff' 应该是 2017 年和 2016 年之间的差异
I would like to subtract one columns from another in a pivot table. 'diff' shoud be the difference between 2017 and 2016
raw_data = {'year': [2016,2016,2017,2017],
'area': ['A','B','A','B'],
'age': [10,12,50,52]}
df1 = pd.DataFrame(raw_data, columns = ['year','area','age'])
table=pd.pivot_table(df1,index=['area'],columns=['year'],values['age'],aggfunc='mean')
table['diff']=table['2017']-table['2016']
解决方案
你需要删除 pivot_table
中的 []
才能不创建 MultiIndex
列:
You need remove []
in pivot_table
for dont create MultiIndex
in columns:
table=pd.pivot_table(df1,index='area',columns='year',values='age',aggfunc='mean')
print (table)
year 2016 2017
area
A 10 50
B 12 52
table['diff']=table[2017]-table[2016]
print (table)
year 2016 2017 diff
area
A 10 50 40
B 12 52 40
另一个可能的解决方案是 droplevel
:
Another possible solution is droplevel
:
table=pd.pivot_table(df1,index=['area'],columns=['year'],values=['age'],aggfunc='mean')
table.columns = table.columns.droplevel(0)
print (table)
year 2016 2017
area
A 10 50
B 12 52
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