How to order by date defaultdict (list) value?

Question

defaultdict(<type 'list'>, {'003': [('Biology', 'A', '04/18/2013'), ('Irdu', 'A' , '04/17/2013')], '002': [('Biology', 'A', '03/01/2013'), ('Math', 'C', '01/10/2 013'), ('Math', 'C', '03/10/2013')], '001': [('Biology', 'B', '05/01/2013'), ('L iterature', 'B', '03/02/2013'), ('Math', 'A', '02/20/2013')]}) 

I want to sort each key by date and get the following output

 defaultdict(<type 'list'>, {'003': [('Irdu', 'A', '04/17/2013'), ('Biology', 'A', '04/18/2013')], '002': [('Math', 'C', '01/10/2013'), ('Biology', 'A', '03/01/2013'), ('Math', 'C', '03/10/2013')], '001': [('Math', 'A', '02/20/2013'), ('Literature', 'B', '03/02/2013'), ('Biology', 'B', '05/01/2013')]}) 

I tried the following but did not think about it?

 accounts = defaultdict(list) sortedData = sorted(accounts.iteritems(), key=operator.itemgetter(2)) 

Answer 1

I think you need something like:

 key = itemgetter(2) sortedData = {} for k, v in accounts.items(): v.sort(key=key) sortedData[k] = v 

or

 sortedData = {(k, list(sorted(v, key=key)) for k, v in accounts.items()} 

Answer 2

iteritems returns an iterator of key / value pairs. If you want to use it, you will have to skip the keys and sort the values. If you want to actually change the defaultdict itself, the best way to post in place is:

 getter = operator.itemgetter(2) for v in accounts.itervalues(): v.sort(key=getter) 

If you want a new defaultdict, you can use a generator expression:

 getter = operator.itemgetter(2) sortedData = defaultdict(list, {k: sorted(v, key=getter) for k, v in accounts.iteritems()}) 

Answer 3

This should do the trick:

 from collections import defaultdict from datetime import datetime d = defaultdict(list, {'003': [('Biology', 'A', '04/18/2013'), ('Irdu', 'A', '04/17/2013')], '002': [('Biology', 'A', '03/01/2013'), ('Math', 'C', '01/10/2013'), ('Math', 'C', '03/10/2013')], '001': [('Biology', 'B', '05/01/2013'), ('Literature', 'B', '03/02/2013'), ('Math', 'A', '02/20/2013')]}) def key(entry): _, _, date_string = entry date_entry = datetime.strptime(date_string, '%m/%d/%Y').date() return (date_entry.year, date_entry.month, date_entry.day) {k: sorted(v, key=key) for k,v in d.iteritems()} >>> { '001': [('Math', 'A', '02/20/2013'), ('Literature', 'B', '03/02/2013'), ('Biology', 'B', '05/01/2013')], '002': [('Math', 'C', '01/10/2013'), ('Biology', 'A', '03/01/2013'), ('Math', 'C', '03/10/2013')], '003': [('Irdu', 'A', '04/17/2013'), ('Biology', 'A', '04/18/2013')] }