I am surprised nobody suggested we put those two methods into a separate module (say dictutils or even UserDict) as functions:
from dictutils import tally, listappend
tally(mydict, key) listappend(mydict, key, value)
Sorry to join the discussion so late (I've been away from my email for a week) but this was exactly my reaction too. In fact, I have a 'dicttools' module with similar methods in it:
# like "tally" but without ability to set increment
def counts(iterable, key=None):
result = {}
for item in iterable:
# apply key function if necessary
if key is None:
k = item
else:
k = key(item)
# increment key's count
try:
result[k] += 1
except KeyError:
result[k] = 1
return result# like "listappend" but with the option to use key and value funcs
def groupby(iterable, key=None, value=None):
result = {}
for item in iterable:
# apply key function if necessary
if key is None:
k = item
else:
k = key(item)
# apply value function if necessary
if value is None:
v = item
else:
v = value(item)
# append value to key's list
try:
result[k].append(v)
except KeyError:
result[k] = [v]
return resultThese two functions have covered all my use cases for "tally" and "listappend" -- I always want to perform the increments or list appends over a sequence of values, so having functions that operate on sequences covers all my needs.
STeVe -- http://mail.python.org/mailman/listinfo/python-list
