pandas 订购了有关考试成绩'D'，...，'A +'的分类数据 [英] Pandas ordered categorical data on exam grades 'D',...,'A+'

问题描述

我在熊猫中有以下数据，我感到惊讶的是输出为:D + A 我期待着A + D

I have the following data in pandas, I was surprized that the output was: D+ A I was expecting A+ D

有人可以解释吗

df = pd.DataFrame(['A+','A','A-','B+','B','B-','C+','C','C-','D+','D'],
                     index = ['excellent','excellent','excellent','good','good','good','ok','ok','ok','poor','poor'])
df.rename (columns={0:'Grades'},inplace=True)
grades = df['Grades'].astype('category', categories = ['D','D+', 'C-', 'C','C+','B-','B','B+','A-','A','A+'],ordered=True)
print(max(grades),min(grades))

> D+ A

推荐答案

max是Python函数，并且不遵守类别排序.它使用基于unicode代码的字典顺序.

max is a Python function and it does not respect the category ordering. It uses lexicographical ordering based on unicode codes.

如果要考虑分类顺序，则需要使用Series/DataFrames上定义的方法:

If you want to take into account categorical orders, you need to use the methods defined on Series/DataFrames:

print(grades.min(), grades.max())

收益

D A+

这篇关于 pandas 订购了有关考试成绩'D'，...，'A +'的分类数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！