Using a data frame column name with glue_data

Question

Hi I have a function in R:

myfunction<-function(.data, pvalue, roundto=2){
glue::glue_data(.x=.data,
"p={format(round(pvalue,digits=roundto),nsmall=roundto}")
}

This works fine when I pass .data$pvalue as pvalue to myfunction()

Ideally I would like not to have to write '.data$' each time, as pvalue will be a column in .data,

I've looked into this and tried quos, {{, !! etc. but get various errors including:

 Error: Quosures can only be unquoted within a quasiquotation context.

  # Bad:
  list(!!myquosure)

  # Good:
  dplyr::mutate(data, !!myquosure)

 Error: Can't convert a `quosure/formula` object to a double vector

If anyone has any suggestions please let me know!

Answer 1

Since glue_data accepts expressions as strings, the easiest thing to do is to capture the input pvalue as a string also:

myfunction<-function(.data, pvalue, roundto=2){
  ## Capture the symbol provided to pvalue and convert it to a string
  v <- rlang::as_name(rlang::ensym(pvalue))

  ## Compose the overall expression string
  s <- paste0("p={format(round(", v, ", digits=roundto),nsmall=roundto)}")

  ## Have glue evaluate the full expression string
  glue::glue_data(.x=.data, s)
}

## Example data
df <- data.frame( pval = c(0.045, 0.678, 0.9) )

## Function works with symbols AND strings
myfunction(df, "pval")
myfunction(df, pval)
# p=0.04
# p=0.68
# p=0.90