R的逐行最大值 [英] rowwise maximum for R

问题描述

我有一个如下数据框.我想为每一行获取一列最大值.但是，如果该列中存在该列，则该列应忽略值9. 我如何有效地做到这一点?

I have a dataframe as below. I want to get a column of maximums for each row. But that column should ignore value 9 if it is present in that row. How can i achive that efficiently?

df <- data.frame(age=c(5,6,9), marks=c(1,2,7), story=c(2,9,1))
df$max <- apply(df, 1, max)    
df

推荐答案

这是一种可能性:

df$colMax <- apply(df, 1, function(x) max(x[x != 9]))

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