pandas 数据框.按值和计数分组 [英] Pandas dataframe. Group by value and count

问题描述

我有下表:

Days, Age,  Sex

5,    39,   F
4,    54,   M
4,    26,   M
5,    42,   M
4,    29,   M

我想分别计算F和M的行数.以下命令有效，但是我对表示形式不满意:

I want to count number of rows with F and M separately. The following command works, but I'm not OK with the representation:

df.groupby("Sex").count()

什么是最好的方法?谢谢.

What will be the best way to do it? Thank you.

推荐答案

只需添加到Wen的答案中即可.或者，可以在使用df.Sex选择列时使用value_counts.

Just to add to Wen's answer. Alternatively, you can use value_counts while selecting the column with df.Sex.

df.Sex.value_counts()
    M    4
    F    1
Name: Sex, dtype: int64

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