向pandas数据帧添加重复计数器列的最简单方法

import pandas as pd

data = {'A': ['foo', 'bar', 'foo', 'bar', 'foo', 'bar'],
        'B': [1, 2, 3, 4, 5, 6]}
df = pd.DataFrame(data)

df['counter'] = df.groupby('A').cumcount() + 1

import pandas as pd

data = {'A': ['foo', 'bar', 'foo', 'bar', 'foo', 'bar'],
        'B': [1, 2, 3, 4, 5, 6]}
df = pd.DataFrame(data)

df['counter'] = df.groupby('A').cumcount() + 1