I am trying to use an OrderedDict (Raymond Hettingers version for pre2.7 Python) where my keys are dates. However it does not order them correctly, I imagine it may be ordering based on the ID.
Does anyone have any suggestions of how this could be done?
OrderedDict, according to its docstring, is a kind of dict that remembers insertion order. Thus, you need to manually insert the key/value pairs in the correct order.
# assuming unordered_dict is a dict that contains your data
ordered_dict = OrderedDict()
for key, value in sorted(unordered_dict.iteritems(), key=lambda t: t[0]):
ordered_dict[key] = value
edit: See utdemir's answer for a better example. Using operator.itemgetter gives you better performance (60% faster, I use the benchmark code below) and it's a better coding style. And you can apply OrderedDict directly to sorted(...).
a = (1, 2)
empty__func = 0
def empty():
for i in xrange(N_RUNS):
empty__func
lambda_func = lambda t: t[0]
def using_lambda():
for i in xrange(N_RUNS):
lambda_func(a)
getter_func = itemgetter(0)
def using_getter():
for i in xrange(N_RUNS):
getter_func(a)
In [1]: from collections import OrderedDict
In [2]: import operator
In [3]: from datetime import date
In [4]: d = {date(2012, 1, 1): 123, date(2010,2,5): 542, date(2011,3,3):76 }
In [5]: d # Good old dict
Out[5]: #it seems sorted, but it isn't guaranteed to be that way.
{datetime.date(2010, 2, 5): 542,
datetime.date(2011, 3, 3): 76,
datetime.date(2012, 1, 1): 123}
In [6]: o = OrderedDict(sorted(d.items(), key=operator.itemgetter(0)))
In [7]: o #Now it is ordered(and sorted, because we give it by sorted order.).
Out[7]: OrderedDict([(datetime.date(2010, 2, 5), 542), (datetime.date(2011, 3, 3), 76), (datetime.date(2012, 1, 1), 123)])
