R：查找具有最高值的列

Question

我想在每一列中找到MAX值，并生成哪一列产生最大值的信息（图片中的黄色单元格）。

感谢帮助。

Answer 1

这是基本的R解决方案

df <- cbind(df,
            do.call(rbind,
                    apply(df[-1], 1, function(v) data.frame(MAX = max(v),Top_Subject = names(v[which.max(v)])))))

这样

> df
    Name Math Physics History Chemistry Biology MAX Top_Subject
1   Jack    9       8       7         7       4   9        Math
2   Andy    6       8       6         5       5   8     Physics
3  Peter    7      10       7         6       8  10     Physics
4 Ashley    7       6       5         6       8   8     Biology

数据

df <- structure(list(Name = c("Jack", "Andy", "Peter", "Ashley"), Math = c(9, 
6, 7, 7), Physics = c(8, 8, 10, 6), History = c(7, 6, 7, 5), 
    Chemistry = c(7, 5, 6, 6), Biology = c(4, 5, 8, 8)), class = "data.frame", row.names = c(NA, 
-4L))

Answer 2

基本的R解决方案（以后请c + p dput（df）函数的输出以生成示例而不是图片）：

df2 <- transform(df, max_scores = apply(df[,sapply(df, is.numeric)], 1, max),
                top_sub_per_stud = names(df[,sapply(df, is.numeric)])[apply(df[,sapply(df, is.numeric)], 1, which.max)])

数据：

df <- structure(list(Name = c("Jack", "Andy", "Peter", "Ashley"), Math = c(9, 
6, 7, 7), Physics = c(8, 8, 10, 6), History = c(7, 6, 7, 5), 
    Chemistry = c(7, 5, 6, 6), Biology = c(4, 5, 8, 8)), class = "data.frame", row.names = c(NA, 
-4L))