R Client for Various CrossRef APIs.

Crossref APIs

rcrossref interacts with the main Crossref metadata search API at https://github.com/CrossRef/rest-api-doc, the old metadata search API at http://search.labs.crossref.org/, their DOI Content Negotiation service at http://citation.crosscite.org/docs.html, and the Text and Data Mining project http://tdmsupport.crossref.org/

Crossref's API issue tracker lives at https://gitlab.com/crossref/issues it's a good place to go ask them about things related to their API that go beyond the R interface here.


See rcrossref-deprecated and rcrossref-defunct for details.

What am I actually searching?

When you use the cr_*() functions in this package, you are using the Crossref search API described at https://github.com/CrossRef/rest-api-doc When you search with query terms, on Crossref servers they are not searching full text, or even abstracts of articles, but only what is available in the data that is returned to you. That is, they search article titles, authors, etc. For some discussion on this, see https://gitlab.com/crossref/issues/issues/101

Rate limiting

From time to time Crossref needs to impose rate limits to ensure that the free API is usable by all. Any rate limits that are in effect will be advertised in the X-Rate-Limit-Limit and X-Rate-Limit-Interval HTTP headers.

This boils down to: they allow X number of requests per some time period. The numbers can change so we can't give a rate limit that will always be in effect. If you're curious pass in verbose = TRUE to your function call, and you'll get headers that will display these rate limits.

Be nice and share your email with Crossref

The Crossref team encourage requests with appropriate contact information and will forward you to a dedicated API cluster for improved performance when you share your email address with them. https://github.com/CrossRef/rest-api-doc#good-manners--more-reliable-service

To pass your email address to Crossref via this client, simply store it as environment variable in .Renviron like this:

  1. Open file: file.edit("~/.Renviron")

  2. Add email address to be shared with Crossref crossref_email = [email protected]

  3. Save the file and restart your R session

Don't wanna share your email any longer? Simply delete it from ~/.Renviron

Text mining

All Crossref specific text mining functions are now deprecated, and moved to a new package crminer.

Another package fulltext is designed solely to do general purpose text mining involving Crossref and other sources of scholarly metadata and full text.

High and Low Level APIs

For the Crossref search API (the functions cr_funders(), cr_journals(), cr_licenses(), cr_members(), cr_prefixes(), cr_types(), cr_works()), there is a high level API and a low level. The high level is accessible through those functions just listed (e.g., cr_works()), whereas the low level is accessible via the same fxn name with an underscore (e.g., cr_works_()). The high level API does data requests, and parses to data.frame's. Since the high level API functions have been around a while, we didn't want to break their behavior, so the low level API functions are separate, and only do the data request, giving back json or a list, with no attempt to parse any further. The low level API functions will be faster because there's much less parsing, and therefore less prone to potential errors due to changes in the Crossref API that could cause parsing errors. Note that cursor feature works with both high and low level.

RStudio Addin

On installation of rcrossref you get an RStudio Addin. To use the Addin, go to the top toolbar > Tools > Addins > Add Crossref Citations. You'll get a window pop up that you can put in DOIs for. If the DOI is found, the bibtex citations will be added to a file called crossref.bib. New citations will be appended to that file. Addin authored by Hao Zhu https://github.com/haozhu233