Top "Autovivification" questions

Autovivification means implicitly creating data structures accessed via name when explicitly creating their data, such as initializing a hash upon assigning the first key/value pair, or creating a folder upon saving a file in a new path.

What is the best way to implement nested dictionaries?

I have a data structure which essentially amounts to a nested dictionary. Let's say it looks like this: {'new jersey': {…

python data-structures dictionary mapping autovivification
What's the best way to initialize a dict of dicts in Python?

A lot of times in Perl, I'll do something like this: $myhash{foo}{bar}{baz} = 1 How would I translate this …

python autovivification
How can I check if a key exists in a deep Perl hash?

If I understand correctly, calling if (exists $ref->{A}->{B}->{$key}) { ... } will spring into existence $…

perl hash autovivification
How to assign hash['a']['b']= 'c' if hash['a'] doesn't exist?

Is there any way simpler than if hash.key?('a') hash['a']['b'] = 'c' else hash['a'] = {} hash['a']['b'] = …

ruby hash variable-assignment autovivification hash-of-hashes