How to extend OrderedDict with defaultdict behavior

Question

I have a list of OrderedDict objects. I would like to combine all of them together and then sort them by the fruit attribute in each of them. I have been trying to combine and sort them using defaultdict using the code below:

super_dict_apple = defaultdict(list)
super_dict_orange = defaultdict(list)
super_dict_no_fruit = defaultdict(list)


for d in dict:
        if 'fruit' not in d:
            for k, v in d.iteritems():
                super_dict_no_fruit[k].append(v)
        elif d['fruit'] == 'Apple':
            for k, v in d.iteritems():
                super_dict_apple[k].append(v)
        elif d['fruit'] == 'orange':
            for k, v in d.iteritems():
                super_dict_orange[k].append(v)  

With this I get one key and all the associated values, but I lose the original order. So I tried to do it with an OrderedDict, but I cannot get it to work. This is what I tried:

from collections import OrderedDict

order_dict_no_fruit = OrderedDict()
order_dict_apple = OrderedDict()
order_dict_orange = OrderedDict()

for d in dict:
        if 'fruit' not in d:
            for k, v in d.iteritems():
                order_dict_no_fruit[k].append(v)
        elif d['fruit'] == 'Apple':
            for k, v in d.iteritems():
                order_dict_apple[k].append(v)
        elif d['fruit'] == 'orange':
            for k, v in d.iteritems():
                order_dict_orange[k].append(v) 

My main goal is to keep the original order of the dictionaries but combine them into three different OrderedDict objects based on the fruit keys.

Kellerman

How does it not work. You should always be able to describe that in detail. – Ridotto

Please show an example of what you're getting and another example of what you expect. – Jae

Likely, it doesn't work because an OrderedDict is not a defaultdict so it doesn't automatically set a default value when accessing. If only there were dict method that setdefault...DOTDOT – Ridotto

Mention input, output you are getting and expected output. – Electroencephalograph

Answer 1

Instead of a regular OrderedDict, try a subclass that adds in defaultdict behavior:

class OrderedDictWithDefaultList(OrderedDict):
    def __missing__(self, key):
        value = list()
        self[key] = value
        return value

Chi

'TypeError: 'type' object has no attribute 'getitem'' – Kellerman

You've got an error elsewhere in your code. Perhaps you left off the parentheses off when instantiating the dictionaries. It should be super_dict_apple = OrderedDictWithDefaultList() instead of super_dict_apple = OrderedDictWithDefaultList. – Chi