diff --git a/snippets/collect_dictionary.md b/snippets/collect_dictionary.md index d02bfefc4..d4b9112cc 100644 --- a/snippets/collect_dictionary.md +++ b/snippets/collect_dictionary.md @@ -5,14 +5,18 @@ tags: dictionary,intermediate Inverts a dictionary with non-unique hashable values. -- Use `dictionary.items()` in combination with a loop to map the values of the dictionary to keys using `dictionary.setdefault()`, `list()` and `append()` to create a list for each one. +- Create a `defaultdict` with `list` as the default value for each key. +- Use `dictionary.items()` in combination with a loop to map the values of the dictionary to keys using `append()`. +- Use `dict()` to convert the `defaultdict` to a regular dictionary. ```py +from collections import defaultdict + def collect_dictionary(obj): - inv_obj = {} + inv_obj = defaultdict(list) for key, value in obj.items(): - inv_obj.setdefault(value, list()).append(key) - return inv_obj + inv_obj[value].append(key) + return dict(inv_obj) ``` ```py