Input column name as variable in a function

Question

I'm trying to write a function that I can use across multiple dataframes which accepts column names as input. The objective is to identify whether an event happened (if it was the earliest) and then code the results into a binary 0 and 1. This is what I've come up with so far:

event <- function(x){
  analysis$event <- 0
  analysis$event[analysis$earliest == analysis$x] <- 1
}

However, when I try it with say test <- event(death_date) it returns just a value of 1. What went wrong and how can I fix it? Thanks!

Possible duplicate https://stackoverflow.com/questions/18222286/dynamically-select-data-frame-columns-using-and-a-character-value — Ronak Shah, Oct 30 '20 at 07:55

score 0 · Accepted Answer · answered Oct 30 '20 at 07:52

0

The dollar operator does not work with variables. You can use double square brackets instead:

col_name <- "mpg"
mtcars[[col_name]]

# compare:
mtcars$mpg

answered Oct 30 '20 at 07:52

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Input column name as variable in a function

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