Have at you, Project Gutenberg…
I am for sure not the first person to think it would be nice to try to make the Project Gutenberg metadata more easily machine tractable. Matthew Jockers wrote a python script to hack usable metadata out of the individual texts back in 2010 (see this blog entry ) ; Damon Cavar wrote some java to do something similar but starting from the RDF form of the Gutenberg catalog, as part of an ambitious
(but I think as yet incomplete) Project Gutenberg to TEI XML conversion project last updated 2012. More recently, Jonathan Reeve has announced an interesting project which is hacking together various bits of Gutenberg, Gitenberg, and Wikipaedia to make a project Gutenberg database for text mining … one day.
My objectives are not so ambitious and I like to keep things simple. I just want to know how many Gutenberg titles are listed in the Bassett database of 19th c British fiction. (I’d also like to be able to extract a list of all British novels in English published for the first time between 1902 and 1920, but that’s a separate problem) Having experimented with other plain text options, I reluctantly decided to start from the Gutenberg RDF catalogue. At least that is expressed using a syntax which xslt can handle and validate. No claims that its semantics are entirely reliable, of course.
Step 1 is to download and unpack a massive zip file from the Gutenberg site. We want the RDF format data is linked to from a page in the Gutenberg wiki: It is massive because it actually contains nigh on 50,000 subdirectories, each containing a single file, describing a single text. So, for example, the RDF format catalogue entry for text number 1234 is in the unpacked file cache/epub /1234/pg1234.rdf When I looked there was also just one directory called DELETE-55495 which contained a variant of the entry for pg55485.rdf, but I pretended I hadn’t noticed that.
Step 2 is to develop and perfect a simple XSLT script to extract the useful grains from the enormous amount of chaff in each RDF file. This script (rdftotei) is designed to meet the needs of the ELTeC, so it rejects anything which is clearly out of the desired time zone (author born after 1920 or before 1800), or definitely not a novel (some records use a marc edt descriptor to show that they are edited compilations). If I could find a way of identifying books which are not in English I would exclude them too. It cranks out simplified TEI bibl records like this:
<bibl xml:id="10037" n="abeautifulpossibility|Black"> <title>A Beautiful Possibility</title> <author dates="1857 1936">Black, Edith Ferguson</author> </bibl>
As you can see, this includes a magic key that I will later use for matching with other ELTeC bibliographic records, notably the Bassett database I blogged about last week.
Step 3 is to find a way of running this script against 50,000 files which does not cause my computer to melt down, and preferably will complete in my lifetime. My first simple minded approach was a shell script that invokes saxon on each file. But this has to set up a JVM afresh each time it runs, so it takes forever. I considered glomming the individual files together into a smaller number of larger files, so that loading the JRE gets done less frequently, but this is fiddly because each of the individual files begins with an XML declaration that would have to be removed during the glomming process. A question to the oxygen users list evinces 3 helpful alternative suggestions in ten minutes: the easiest and quickest of which is to use a feature I didn’t even know existed in saxon: specifying a directory as input and as output. So with all my RDF files in the folder RDF and nothing in the directory RDFx, I do the following two shell commands:
saxon -s:RDF -o:RDFx rdftotei.xsl cat RDFx/* > gutenList.xml
and the whole thing is done in a couple of minutes.
Step 4 is to repeat the process as before: pick out the magic keys and then look for overlaps between those keys and those in the Bassett database (like this:
saxon guten-list.xml getKeys.xsl > gutenKeys.txt comm -12 <(sort gutenKeys.txt) <(sort bassetKeys.txt)
Result on the first round: 1478 Gutenberg titles are already known to Bassett. Not as many as I’d expected, but not bad. Here are the full results for all three digital collections.
Out of 13,859 titles in Bassett’s database, a total of 2937 appear in at least one of Gutenberg, Internet Archive, Google Books, or VWWP, i.e. more than 20% (which is better than I was expecting). Here are the counts for the individual collections:
Also to be expected, there’s a bit of overlap. 2638 appear in only one digital collection; 276 in two, and 23 in all 3. You can probably guess which titles those are, though one of them came as a bit of a surprise. What’s so great about Mary Ward’s « Marcella »?.