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-- Tries to filter down a large CDX file to a subset that is likely to be
-- journal article content, based on SURT regex patterns.
---
-- Author: Bryan Newbold <bnewbold@archive.org>
-- Date: May 2018
%default INPUT ''
%default OUTPUT ''
set mapreduce.job.queuename default
cdx = LOAD '$INPUT' AS cdxline:chararray;
cdx = FILTER cdx BY not STARTSWITH (cdxline, 'filedesc');
cdx = FILTER cdx BY not STARTSWITH (cdxline, ' ');
cdx = FOREACH cdx GENERATE STRSPLIT(cdxline,'\\s+') as cols, cdxline;
cdx = FOREACH cdx GENERATE (chararray)cols.$0 as surt, (chararray)cols.$1 as timestamp, (chararray)cols.$3 as mimetype, (chararray)cols.$4 as httpstatus, cdxline;
cdx = FILTER cdx BY not surt matches '-';
cdx = FILTER cdx BY httpstatus matches '200';
cdx = FILTER cdx BY mimetype matches '.*pdf.*';
-- This is the core regex
cdx = FILTER cdx
-- academic domains; personal (tilde) directories
BY surt matches '(edu,|..,edu|..,ac,).*\\).*\\/~.*'
-- words in URL
OR surt matches '(?i).+\\).*/(pubs|research|publications?|articles?|proceedings?|papers?|fulltext)/.*'
-- words in domains
OR surt matches '.*(,hal|,eprint|scielo|redalyc|revues|revistas|research|journal).*\\).*'
-- DOI-like pattern in URL
OR surt matches '.*\\).*/10\\.\\d{3,5}/.*';
cdx = ORDER cdx by surt, timestamp PARALLEL 50;
cdx = FOREACH cdx GENERATE cdxline;
STORE cdx INTO '$OUTPUT' USING PigStorage(' ');
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