From 367a747ad713a79e19d48814f76a26ead1d241f2 Mon Sep 17 00:00:00 2001 From: Helmut Irle Date: Sat, 10 Oct 2020 23:16:53 +0200 Subject: [PATCH] Better readability for appending to list. --- snippets/collect_dictionary.md | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/snippets/collect_dictionary.md b/snippets/collect_dictionary.md index d02bfefc4..85a50660e 100644 --- a/snippets/collect_dictionary.md +++ b/snippets/collect_dictionary.md @@ -5,13 +5,15 @@ 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. +- Use `dictionary.items()` in combination with a loop to map the values of the dictionary to keys using `collections.defaultdict`, `list()` and `append()` to create a list for each one. ```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) + inv_obj[value].append(key) return inv_obj ```