pandas 分组groupby方法

import pandas as pd
import numpy as np

df = pd.DataFrame({"A": ["foo", "bar", "foo", "bar", "foo", "bar", "foo", "foo"],
                   "B": ["one", "one", "two", "three", "two", "two", "one", "three"],
                   "C": np.random.randn(8),
                   "D": np.random.randn(8)})
print(df)

输出如下：

使用groupby分组，并且求和

print(df.groupby("A").sum())

分组后的结果：

按照两列分组

df.groupby(["A", "B"]).sum()

输出：