python-3.x - 如何查找另一列的不同行中具有多个值的列值的总长度

Question

有没有办法找到同时有Apple和Strawberry的ID，然后求总长度？以及只有 Apple 的 ID，以及只有 Strawberry 的 IDS？

df:

        ID           Fruit
0       ABC          Apple        <-ABC has Apple and Strawberry
1       ABC          Strawberry   <-ABC has Apple and Strawberry
2       EFG          Apple        <-EFG has Apple only
3       XYZ          Apple        <-XYZ has Apple and Strawberry
4       XYZ          Strawberry   <-XYZ has Apple and Strawberry 
5       CDF          Strawberry   <-CDF has Strawberry
6       AAA          Apple        <-AAA has Apple only

期望的输出:

Length of IDs that has Apple and Strawberry: 2
Length of IDs that has Apple only: 2
Length of IDs that has Strawberry: 1

谢谢!

Answer 1

如果 Fruit 列中的所有值始终仅为 Apple 或 Strawberry，您可以比较每组的集合，然后计算 ID 通过 True 值的 sum:

v = ['Apple','Strawberry']
out = df.groupby('ID')['Fruit'].apply(lambda x: set(x) == set(v)).sum()
print (out)
2

编辑:如果有很多值:

s = df.groupby('ID')['Fruit'].agg(frozenset).value_counts()
print (s)
{Apple}                2
{Strawberry, Apple}    2
{Strawberry}           1
Name: Fruit, dtype: int64