124 simple version of business logic

[NYSAG-GS]

Heavily inspired by the Architecture Patterns with Python book, I wondered what the domain layer might look like if it were completely unencumbered by database implementation logic? The oagdedupe/simple module is an attempt at that.

The most basic concepts are

• Record
  • a row of data
  • defined by its values (so record1 == record2 <=> record1.values == record2.values)
  • implemented here as a frozendict (an immutable dict) so I can put Records in a Set
• Entity
  • a set of Record objects (the records determined to be referencing that entity)

And some abstractions like

• Signature
  • anything you define equality on
  • primary use case here is ngram schemes: signature is a set of strings, and equality between two sets is whether or not there is an intersection

The top-level API has a get_entities method that finds the best conjunctions (not implemented), gets pairs, classifies pairs, and clusters records based on those classifications.

There's a lot here that isn't implemented yet, but basic tests using fakes pass. Interested in your thoughts @chansooligans, I have some thoughts on how this could be useful besides an interesting toy model.

[NYSAG-GS]

Merging as the changes are purely additive (I just did a rebase from master, I hope this doesn't mess anything up but will keep the commit history around if it does)