pyra 0.2.3dev

pyra - Python Region Algebra

Pyra is a python implementation of the region query algebra described in [1]. Region algebras are used to efficiently query semi-structured text documents. For a quick online introduction to this region algebra, and why it is useful, visit the [Wumpus Search Docs](http://www.wumpus-search.org/docs/gcl.html). In general, region algebras are good for extracting data from documents that have lightweight structure (semi-structured), and are an alternative to more heavyweight solutions like XPath queries.

# Setup the corpus corpus = “the quick brown fox jumps over the lazy dog and the brown dog runs away” tokens = corpus.split()

# List regions starting with ‘brown’ and ending with ‘dog’, containing # the phrase ‘fox jumps over’.

iidx = InvertedIndex(tokens) g = GCL(iidx)

for s in g.Contains( g.BoundedBy( g.Term(‘brown’), g.Term(‘dog’) ), g.Phrase(‘fox’, ‘jumps’, ‘over’) ):

print s print “’%s’” % (tokens[s],)

The above prints:

slice(2,9)

‘brown fox jumps over the lazy dog’

References

[1] Clarke, C. L., Cormack, G. V., & Burkowski, F. J. (1995). An algebra for structured text search

and a framework for its implementation. The Computer Journal, 38(1), 43-56. Chicago