CODEWITHSUNDEEP
pythondictionary
Alex C
Alex C

Reputation: 171

Longest set in a dict of sets

I have a defaultdict of sets and I need to align columns nicely during final output
Each set is displayed via ",".join(setdict[key]) to avoid ugly braces
I'm wondering is there more efficient and Pythonic way to calc longest set's string with commas
My current implementation is

def GetSetLen(setdict):
    maxset = 0
    for k,v in setdict.iteritems():
        maxset = max(maxset, (len(",".join(setdict[k]))))
    return maxset

Real example of my dict:

defaultdict(<type 'set'>, {'2235788': set(['604', '2415919103', '7']), '3674877': set(['604', '2415919103', '7'])})

Upvotes: 0

Views: 79

Answers (2)

wwii
wwii

Reputation: 23773

map str.join on the values ,then map len on the resultant strings, then find the max

>>> 
>>> d
defaultdict(<type 'set'>, {'2235788': set(['604', '2415919103', '7']), '654321': ['60004', '2415919103', '765'], '000002': ['', '', ''], '000000': [''], '3674877': set(['604', '2415919103', '7']), '123456': ['604', '2415919103', '765']})
>>> map(len, map(','.join, d.itervalues()))
[16, 20, 2, 0, 16, 18]
>>> max(map(len, map(','.join, d.itervalues())))
20
>>>

You could use itertools.imap if you didn't want to create the intermediate lists.

Upvotes: 0

falsetru
falsetru

Reputation: 369314

Use dict.itervalues because the code does not take account of keys. And you don't need to make a temporary string to calculate length of the joined strings.

if not setdict:
    return 0  # max(empty_setdict) raise a `ValueError`
return max(sum(map(len, v)) + len(v) - 1 if v else 0
           for v in setdict.itervalues())

Upvotes: 1

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