根据 Pandas 数据框中其他列的值设置列的值 [英] Setting value of a column based on values of other columns in Pandas dataframe

问题描述

我有这个 Pandas 数据框:

I have this Pandas dataframe:

这是关于两国间板球比赛的一些虚构数据.我想根据这个简单的逻辑设置列获胜者的值:

This is some fictional data about games of cricket played between two countries. I want to set the value of column winner based on this simple logic:

if country_1_runs == country_2_runs:
    winner = 3
elif country_1_runs > country_2_runs:
    winner = 1
else:
    winner = 2

我了解 Pandas 中的 map 和 apply 方法.但我不确定它们是否允许上述条件表达式.

I know about map and apply methods in Pandas. But I'm not certain if they allow conditional expressions like the above.

推荐答案

使用 numpy.select:

m1 = df.country_1_runs == df.country_2_runs
m2 = df.country_1_runs > df.country_2_runs

df['winner'] = np.select([m1, m2], [3, 1], default=2)

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