I don't know how to do this:
I have a list of lists defined like this:
list=[[day,type,expense],[...]];
day and expense are int, type is string
I need to find the max expense by day. An example:
list=[[1,'food',15],[4,'rent', 50],[1,'other',60],[8,'bills',40]]
I need to sum the elements that have the same day and find the day with the highest expenses.
The result should be:
day:1, total expenses:75
Isn't a defaultdict just as easy?
import pprint
from collections import defaultdict
from operator import itemgetter
l = [[1, 'food', 15], [4, 'rent', 50], [1, 'other', 60], [8, 'bills', 40]]
d = defaultdict(int)
for item in l:
d[item[0]] += item[2]
pprint.pprint(dict(d))
print max(d.iteritems(), key=itemgetter(1))
Result:
{1: 75, 4: 50, 8: 40}
(1, 75)
data=[[1,'food',15],[4,'rent', 50],[1,'other',60],[8,'bills',40]]
# put same days together
data.sort()
# aggregate the days
from itertools import groupby
from operator import itemgetter
grouped = groupby(data, key=itemgetter(0))
# sum values by day
summed = ((day, sum(val for (_,_,val) in day_group))
for day, day_group in grouped)
# get the max
print max(summed, key=itemgetter(1))
groupby too, but if the data is unsorted I think a defaultdict is more natural. Random suggestions: I'd use an itemgetter key function for the sort too so as to avoid doing extra comparisons. Also, if you're going to use itemgetter for the key functions (I realize those have to be functions), why not also use it for the summing (even though you don't have to use a function there)? valgetter = itemgetter(2) then a generator expression or map with valgetter -- sum(map(valgetter, day_group)).list = [[1, 'food', 15], [4,'rent', 50], [1, 'other', 60], [8, 'bills', 40]]
hash = {}
for item in list:
if item[0] not in hash.keys():
hash[item[0]] = item[2]
else:
hash[item[0]] += item[2]
for (k, v) in hash:
# print key: value
or if you just want the most expensive day.
for (k, v) in hash:
if (v == max(hash.values()):
#print k: v
