I need to efficiently store data in something that would resemble a "dictionary of sets" e.g. have a dictionary with multiple (unique) values matching each unique key. The source of my data would be a (not very well) structured XML.
My idea is: I will look through a number of elements and find keys. If the key does not exist, add it to dictionary, if it already exists, just add a new value in the corresponding key.
And the result would be something like:
{
'key1': {'1484', '1487', 1488', ...}
'key2': {'1485', '1486', '1489', ...}
'key3': {'1490', '1491', '1492', ...}
...
}
I need to add new keys on the go. I need to push unique values into each set. I need to be able to iterate through the whole dictionary.
I am not sure if this is even feasible, but if anybody could push me in the right direction, I would be more than thankful.
I'm not going to benchmark this but in my experience native dicts are faster
store = {}
for key, value in yoursource:
try:
store[key].add(value)
except KeyError:
store[key] = {value}
from collections import defaultdict
mydict = defaultdict(set)
mydict["key1"] |= {'1484', '1487', '1488'}
Iteration is just like the normal dict.
Using dict.setdefault() to create the key if it doesn't exist, and initialising it with an empty set:
store = {}
for key, value in yoursource:
store.setdefault(key, set()).add(value)