url_param takes a vector of URLs and extracts the value associated with
a specified parameter
Usage
url_param(urls, parameter)
Arguments
urls
a vector of URLs.
parameter
the name of the parameter to search for. Case sensitive (so preprocessing
with tolower may be useful).
Value
a character vector containing the value retrieved from each URL.
Details
People tend to put useful data in URL parameters, particularly around
APIs. Extracting these is a pain unless you have a very consistent API, since you're essentially
doing partial string-matching with a potentially arbitrary number of characters to include.
url_param accepts a vector of URLs, and the name of the parameter (without an equals sign)
and returns the value associated with that parameter. In the case that the parameter
is represented multiple times within the URL, the first instance will be used.