defaultdict

I'm using this gist's defaultdict one-line tree. def tree(): return defaultdict(tree) Currently, you must provide a separate [] for every node you want to add. ie: users = tree() users['harold']['username']['hrldcpr'] users['handler']['username']['matthandlersux'] My question is, how would I be able to flatten the input so that I could provide a list to achieve the same result? ie: users = tree() users['harold', 'username', 'hrldcpr'] users['handler', 'username', 'matthandlersux'] Thanks for any help! You can simply define a funcion, say insert to create the node by providing a list and tree

This question already has an answer here: How can this function be rewritten to implement OrderedDict? 3 answers I created a empty defaultdict(list) , and I am adding to it. I want the keys to be sorted in the order of addition. My code takes an input. Input: 4 bcdef abcdefg bcde bcdef My Code: from collections import defaultdict d = defaultdict(list) a = int(input()) for i in range(a): temp = raw_input() d[temp].append(i) for k in d: print k Output: bcde bcdef abcdefg Desired Output bcdef abcdefg bcde You can use collections.OrderedDict to maintain the order of the insertion of keys. >>> from

I am a bit confused on why you need a lambda function for nesting defaultdict Why can't you do it like this? test = defaultdict(defaultdict(list)) instead of test = defaultdict(lambda:defaultdict(float)) test = defaultdict(defaultdict(list)) Because defaultdict requires that you give it something that can be called to create keys for missing values. list is such a callable, but defaultdict(list) is not. It's a defaultdict instance, and you can't call a defaultdict . The lambda is a function that, when called, returns a value that can be used in the dictionary, so it works. Essentially,

My code currently has to count things in a heavily nested dict into another. I have items that need to be indexed by 3 values and then counted. So, before my loop, I initialize a nested defaultdict like so: from collections import defaultdict type_to_count_dic = defaultdict( lambda: defaultdict( lambda: defaultdict(int) ) ) Which allows me to count the items within a tight loop like so: for a in ...: for b in ...: for c in ...: type_to_count_dic[a][b][c] += 1 I feel like initializing all those defaultdict s feels a lot like making a type declaration in something like Java. Is there a more