Implementation of set reconciliation algorithm

Question

I\'m looking for implementations of set reconciliation algorithm. The problem is following: there are two sets with elements identified by some relatively compact value (e.g. UU

Answer 1

This code is out of my head, and thus covered by whatever license applies for code samples in this site.

# given two finite sequences of unique and hashable data,
# return needed opcodes and data needed for reconciliation

def set_reconcile(src_seq, dst_seq):
    "Return required operations to mutate src_seq into dst_seq"
    src_set= set(src_seq) # no-op if already of type set
    dst_set= set(dst_seq) # ditto

    for item in src_set - dst_set:
        yield 'delete', item

    for item in dst_set - src_set:
        yield 'create', item

Use as follows:

for opcode, datum in set_reconcile(machine1_stuff, machine2_stuff):
    if opcode == 'create':
        # act accordingly
    elif opcode == 'delete':
        # likewise
    else:
        raise RuntimeError, 'unexpected opcode'