在 R 中，如何根据其他列的列标题的值创建新列

Question

I have a dataframe as below:

Type    Prob_A prob_B  prob_C
Vinyl    .57    .43       0
Wood     .2     .4       .4
Ceramic  .12    .80      .08

I need to create a new column called Status. Check the probabilities and get the heading of the max value and call it as A, B or C. In my real data asset, I have 10 columns I need to compare.

Answer 1

We can use max.col to get the column index of the first max values and select the substring of the column names

df1$Status <- substring(names(df1)[-1], 
          nchar(names(df1)[-1]))[max.col(df1[-1], 'first')]
df1$Status
#[1] "A" "B" "B"

data

df1 <- structure(list(Type = c("Vinyl", "Wood", "Ceramic"), Prob_A = c(0.57, 
0.2, 0.12), prob_B = c(0.43, 0.4, 0.8), prob_C = c(0, 0.4, 0.08
)), class = "data.frame", row.names = c(NA, -3L))