Function not working with a second argument when using tidyr::extract

Question

I wrote a function to extract links from a string. It works fine when I pass the dataframe as an argument, but not when I want to pass the columnname string as a second argument.

The working function with one argument:

library(tidyr)     
extractLinks <- function(x) {

  # get all links in new column "url"
  df <- tidyr::extract(x, string, "url", "(http.*)")

  #get clean links and domains
  df <- tidyr::extract(df, url, c("site", "domain"), "(http.*\\.(com|co.uk|net))", remove = F)

  return(df)
}

extractLinks(df, string)

Now I want to add the second argument, but it returns an error:

Error in names(l) <- enc2utf8(into) : 
  'names' attribute [1] must be the same length as the vector [0] 

This is my function with two arguments:

extractLinks <- function(x, y) {

  # get all links in new column "url"
  df <- tidyr::extract(x, y, "url", "(http.*)")

  #get clean links and domains
  df <- tidyr::extract(df, url, c("site", "domain"), "(http.*\\.(de|com|at|ch|ly|co.uk|net))", remove = F)
  return(df)
}

extractLinks(df, string)

For replication, an example dataframe:

string
my text in front of the link http://www.domain.com
my text in front of the link http://www.domain.com
my text in front of the link http://www.domain.com

Any idea what's wrong?

Answer 1

You need to use the standard evaluation variant extract_() and turn your second argument into a string:

  # get all links in new column "url"
  df <- tidyr::extract_(x, y, "url", "(http.*)")

extractLinks(df, "string")