How to pass a column name as parameter to a function?

Question

Here is a toy example:

df <- data.frame(user=c('a','b'), rating=c(1,2), age=c(17,33))

rating <- function(df, var){x <- df %>% summarise(sum(var))}

rating(df,age)

When I execute the function, I get the following error:

Error in summarise_impl(.data, dots) : object 'age' not found

How to pass a column name as parameter to the function?

Have you seen this? https://stackoverflow.com/a/26724721/322912 — Roman Luštrik, Sep 15 '17 at 13:12
It's a bit outdated, i am going to try what udden is suggesting. — ronencozen, Sep 15 '17 at 13:31

score 5 · Accepted Answer · answered Sep 15 '17 at 13:19

5

library(tidyverse)

df <- data.frame(user=c('a','b'), 
                 rating=c(1,2), 
                 age=c(17,33))

rating <- function(df, var){
  var <- enquo(var)
  df %>% summarise(sum(!!var))
  }

x <- rating(df,age)

answered Sep 15 '17 at 13:19

udden2903

783
6
15

Error in enquo(var) : could not find function "enquo" – ronencozen Sep 15 '17 at 13:33
1

Try installing dplyr again. The code uses features from the latest release: https://blog.rstudio.com/2017/06/13/dplyr-0-7-0/ – udden2903 Sep 15 '17 at 13:34
Thanks, it's working. – ronencozen Sep 15 '17 at 13:40

How to pass a column name as parameter to a function?

1 Answers1