To select a couple columns from a dataframe I can do
require(dplyr)
require(magrittr)
df <- data.frame(col1=c(1, 2, 3), col2=letters[1:3], col3=LETTERS[4:6])
df %>%
select(col1, col2)
I want to write a function similar to
f <- function(data, firstCol, secondCol){
data %>%
select(substitute(firstCol), substitute(secondCol))
}
But running f(df, col1, col2)
gives me the error
Error in select_vars(names(.data), ..., env = parent.frame()) :
(list) object cannot be coerced to type 'double'
Called from: (function ()
{
.rs.breakOnError(TRUE)
})()
EDIT -- slightly less trivial example:
Suppose I wanted to do
mtcars %>%
select(cyl, hp) %>%
unique %>%
group_by(cyl) %>%
summarise(avgHP = mean(hp))
but with different datasets and different variable names. I could reuse the code and replace mtcars
, cyl
, and hp
. But I'd rather wrap it all up in a function