On Thu, May 7, 2009 at 2:23 PM, Kevin D. Smith <kevin.sm...@sas.com> wrote:
> I need the behavior of heapq.merge to merge a bunch of results from a
> database. I was doing this with sorted(itertools.chain(...), key=...), but
> I would prefer to do this with generators. My issue is that I need the key=
> argument to sort on the correct field in the database. heapq.merge doesn't
> have this argument and I don't understand the code enough to know if it's
> possible to add it. Is this enhancement possible without drastically
> changing the current code?
I think so. Completely untested code:
def key(ob):
#code here
class Keyed(object):
def __init__(self, obj):
self.obj = obj
def __cmp__(self, other):
return cmp(key(self.obj), key(other.obj))
def keyify(gen):
for item in gen:
yield Keyed(item)
def stripify(gen):
for keyed in gen:
yield keyed.obj
merged = stripify(merge(keyify(A), keyify(B), keyify(C))) #A,B,C being
the iterables
Cheers,
Chris
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