Regular expression and script for parsing and sorting Library of Congress Classification call numbers

parsecallno.py

import re

myfile = open('list', 'r')

callnos = myfile.readlines()

p = re.compile("""^(?P<aclass>[A-Z]{1,3})
		  (?P<nclass>\\d{1,4})(\\ ?)
		  (\\.(?P<dclass>\\d{1,3}))?
		  (?P<date>\\ [A-Za-z0-9]{1,4}\\ )?
		  ([\\ \\.](?P<c1>[A-Z][0-9]{1,4}))
		  (\\ (?P<c1d>[A-Za-z0-9]{0,4}))?
		  (\\.?(?P<c2>[A-Z][0-9]{1,4}))?
		  (\\ (?P<e8>\\w*)\\ ?)?
       		  (\\ (?P<e9>\\w*)\\ ?)?
		  (\\ (?P<e10>\\w*)\\ ?)?""",
		  re.VERBOSE)

def ncmp(x,y):
	if x is None and y is None:
		return 0
	if x is None:
		return -1
	if y is None:
		return 1
	x = int(x)
	y = int(y)
	return cmp(x,y)

def sortfunc(x, y):
	xp = p.search(x)
	yp = p.search(y)
	parts = {'aclass':cmp,'nclass':ncmp,'dclass':ncmp,'date':cmp,'c1':cmp,'c1d':cmp,'c2':cmp,'e8':cmp,'e9':cmp,'e10':cmp}
	for part in parts:
		cr = parts[part](xp.group(part),yp.group(part))
		if cr != 0:
			return cr

def normalize(callno):
	cp = p.search(callno)
	out = cp.group('aclass') + cp.group('nclass')
	if cp.group('dclass') is not None:
		out += "."+cp.group('dclass')
	if cp.group('date') is not None:
                out += " "+cp.group('dclass')+ " "
	out += "."+cp.group('c1')
	if cp.group('c1d') is not None:
                out += " "+cp.group('c1d')+ " "
	if cp.group('c2') is not None:
		out += " "+cp.group('c2')
	if cp.group('e8') is not None:
                out += " "+cp.group('e8')
	if cp.group('e9') is not None:
                out += " "+cp.group('e9')
	if cp.group('e10') is not None:
                out += " "+cp.group('e10')
	return out

callnos.sort(sortfunc)

for callno in callnos:
	print "%25s %25s" % (callno.strip(), normalize(callno).strip())

Hello,

I admire this bit of code very much. Since I am a python newb, would you mind demonstrating how to use it, especially the sortfunc()?

Thank you.

Hi, thanks for all your work on this script. I've been experimenting with it and noticed that this sequence:

HA37 .C22 C87 2002
H61 .M5 2000 
H61 .K24
H61 .G593 2006
H35 .L54
H53 .U5 S5 2006

Is sorted in this order:

                 H35 .L54                   H35.L54
           H61 .G593 2006             H61.G593 2006
                 H61 .K24                   H61.K24
             H61 .M5 2000               H61.M5 2000
          H53 .U5 S5 2006           H53.U5 S5  2006
       HA37 .C22 C87 2002        HA37.C22 C87  2002

Shouldn't the H53 appear before the H61?