Here's a link to an XML mapping of LC call numbers ranges to categories that we use in an indexing software. It may be a bit hefty for your needs (almost 6000 mappings), but hope it helps!
From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of Ken Irwin
Sent: Tuesday, September 02, 2014 4:42 PM
To: [log in to unmask]
Subject: [CODE4LIB] library of congress call number subject coding
Does anyone have a handy scheme for coding LC call numbers into just a few broad subject areas (e.g. Arts, Humanities, Sciences, Social Sciences) or perhaps something only a little more granular than that?
I'm hoping for a list that will turn 1-3 letter LC classes into subject groups, and I'd rather not reinvent the wheel if someone's already got something.