python - Pandas :groupby索引然后使用函数填充数据框

Question

我有一个这样的数据框:

df = pd.DataFrame({'pop1': ['1000', '2000','3000','4000'],
                   'pop2': ['2000', '3000','2000','2000']},
                  index=['female','female','male','male'])

我如何创建一个 2*2 DataFrame 来给出给定年份(2 列)中给定性别(2 行)的总人口百分比？

Answer 1

您需要先通过 astype 将 string 转换为 int , 然后 groupby聚合 sum 并除以 div通过 sum .最后多个100:

df = df.astype(int)

a = df.groupby(level=0).sum()
print (a)
        pop1  pop2
female  3000  5000
male    7000  4000

b = df.sum()
print (b)
pop1    10000
pop2     9000
dtype: int64

print (a.div(b).mul(100))
        pop1       pop2
female  30.0  55.555556
male    70.0  44.444444

它等同于:

df = df.astype(int)
print (df.groupby(level=0).sum().div(df.sum()).mul(100))
        pop1       pop2
female  30.0  55.555556
male    70.0  44.444444