Simple demo of map_xml feature of pymarc library & comparing country value in folder of marc xml to records in django db

extract_008_15_17.py

'''
Demo of an implementation of the pymarc library found here:
http://pypi.python.org/pypi/pymarc/

What does this script do?
Returns a list of country counts in a folder of Marc xml records &
coorsponding records that exist in the current database. This is used to help
understand how close the Marc xml records are to the existing ChronAm dataset.

To run this file: python extract_cntry_from_worldcatrecs.py $path_to_bib_folder
Example: python extract_cntry_from_worldcatrecs.py 'bib_recs/bib'

#TODO: Make this more generic to use with other fields.

'''

import glob
import operator
import os
import sys

from pymarc import map_xml
from django.db.models import Count
from chronam.core.models import Country

# FOLDER should be the location of the marcxml files.
FOLDER = sys.argv[1]

marc_countries = {}

def get_record_cntry(record):
    try:
        country_code = record['008'].data[15:18].strip()
    except TypeError:
        # This is a nonetype we are choosing to ignore
        return
    try:
        marc_countries[country_code]+=1
    except KeyError:
        marc_countries[country_code]=1

if __name__ == '__main__':
    os.chdir(FOLDER)
    for file in glob.glob("*.xml"):
        map_xml(get_record_cntry, open(file, 'r'))

    # This is where we output and compare to existing records.
    print ', '.join(['Code','Name','# of recs from OCLC','# of titles in db','difference'])

    db_countries = Country.objects.annotate(title_count=Count('title'))

    for cntry in db_countries:
        db_count = cntry.title_count
        if not db_count:
            continue

        try:
            marcxml_count = marc_countries[cntry.code]
        except KeyError:
            marcxml_count = 0
        
        name = cntry.name
        diff = marcxml_count - db_count
        output = [cntry.code, name, str(marcxml_count), str(db_count), str(diff)]
        print ', '.join(output)