IF TRUE then Variable name-CodePudding

I have a series of TRUE and FALSE variables representing search findings, ex: Cellphones, Knifes, Money, etc. My goal is to change the values TRUE for the name of the variable. Note that I would like to do this for 15 or more variables.

df <- data.frame(cellphone = c(TRUE, TRUE, FALSE, TRUE, FALSE),
                 money = c(FALSE, FALSE, FALSE, TRUE, FALSE),
                 knife = c(TRUE,TRUE,FALSE, FALSE, FALSE),
                 whatIneed = c("cellphone", "cellphone", "", "cellphone",""))

  cellphone money knife whatIneed
1      TRUE FALSE  TRUE cellphone
2      TRUE FALSE  TRUE cellphone
3     FALSE FALSE FALSE          
4      TRUE  TRUE FALSE cellphone
5     FALSE FALSE FALSE

CodePudding user response：

In base R, an option is to loop over the subset of columns that are logical rowwise, get the first column name based on the logical vector

df$whatIneed <- apply(df[1:3], 1, function(x) names(x)[x][1])
df$whatIneed
[1] "cellphone" "cellphone" NA          "cellphone" NA

If we want to do this individually on each column

library(dplyr)
df %>%
    mutate(across(where(is.logical),
      ~ case_when(.x ~ cur_column()), .names = "{.col}_name"))

-output

cellphone money knife whatIneed cellphone_name money_name knife_name
1      TRUE FALSE  TRUE cellphone      cellphone       <NA>      knife
2      TRUE FALSE  TRUE cellphone      cellphone       <NA>      knife
3     FALSE FALSE FALSE                     <NA>       <NA>       <NA>
4      TRUE  TRUE FALSE cellphone      cellphone      money       <NA>
5     FALSE FALSE FALSE                     <NA>       <NA>       <NA>