How do I loop a code over all columns in R?

Question

Package:

install.packages("pROC") 

library(pROC)

The dataset looks like this: Dataset #Apologies for not including the actual dataset

I am trying to apply the roc() code across all columns starting from column 3:

roc1 <- roc(df$Immunoscore,df$col_name)

Currently, I was thinking of doing a lapply method.

list_of_AUC <- lapply(3:ncol, function(i){

roc(RD0161_Final$Immunoscore, RD0161_Final[,i])})

I'm getting a mistake:

Error in 3:ncol : NA/NaN argument

Is there a better method? please help!

Answer 1

Does this work for you?

lapply(RD0161_Final[,3:9], function(i) {
      roc(RD0161_Final[,2] ~ i)
}

Alternatively, you could specify the column name

lapply(RD0161_Final[,3:9], function(i) {
      roc(RD0161_Final[["Immunoscore"]] ~ i)
}

Answer 2

Try this code -

list_of_AUC <- lapply(RD0161_Final[-(1:2)], function(x) roc(RD0161_Final$Immunoscore, x))

You can also use 3:ncol(RD0161_Final) to subset the dataframe.

list_of_AUC <- lapply(RD0161_Final[3:ncol(RD0161_Final)], function(x) roc(RD0161_Final$Immunoscore, x))