Sorting dictionaries?

razorborne

Is there a way to sort a dictionary by key, so that if I pull out an array from it via keys() or values() (or just iterate over it with a for-loop) I get things in a specific order? Like, say I wanted to use a dictionary to store my inventory, like this:

var inventory = {"Bomb": 2, "Ether": 1, "Potion": 5}

So far, it's alphabetical, so if I use a for-loop to display that inventory to the player, it'll be in the correct order. But if I pick up 20 arrows, just going:

inventory["Arrow"] = 20

Will, if I'm understanding correctly, put it at the end of the list because that's when it was added. Is there an easy way to tell it it should put it at the appropriate spot in alphabetical order (or a custom order) so that when I try to use it, I get the same list regardless of which things were added when? I checked the documentation for dictionaries and it doesn't mention any kind of sort function. So far the best way I've come up with to do that is to have a separate, pre-sorted array with the correct order, then just iterate over that instead and use an if to check if each item in the array has a value in the dictionary, but that seems really inefficient and I assume I'm missing something much more straightforward.

Jesusemora

razorborne Dictionaries are unsorted. here and in all languages.

you can use an array to store the keys and sort it, then use the values as keys for the dictionary.

var karray : Array = []
for i in dict:
     karray.append(i)
karray.sort()
for i in karray:
     var tmp = dict.get(i, null)
     if tmp != null:
          pass#etc

xyz

razorborne Strictly speaking, the concept of sorting doesn't make sense for hash mapped data structures like dictionaries. Most languages don't guarantee any order. However, GDScript specifically guarantees the order of iteration over dictionary elements to be the same as the order of insertion. So you can re-insert the elements in the wanted order which will act kinda like sorting.

razorborne

xyz Thanks! I was gonna write a function to do something like this, just seemed like it'd be useful enough that it might already exist so I wanted to check before doing it myself.

DaveTheCoder

Use Jesusemora's advice on this topic. It's more reliable than xyz's.

xyz

DaveTheCoder Use Jesusemora's advice on this topic. It's more reliable than xyz's.

More reliable by which criteria?
The docs are explicit:

Dictionaries will preserve the insertion order when adding new entries

Don't see anything unreliable here.

Moreso if we peek into HashMap and HashMapElement template classes in the hash_map.h, we can see that hashed elements are internally kept in a linked list. All member functions that operate sequentially on the elements as well as all iterators (e.g. HashMap::Iterator) - use the linked list traversal. That's a quite reliable guarantee that the sequential order of elements will always be the same.