How to check if a sparse Array index is empty?

Help Programming
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1

(I figured out the solution while writing this up, but I’m posting it since I spent a while searching, and it might be useful to other people who have gotten used to thinking pythonically.)

Godot Version

4.4.1

Question

In GDScript, how do I check if an Array (a sparse one) has a member at a certain arbitrary index? Even arr[0] throws an exception if nothing has been stored in the array at all, so I can’t check e.g. if arr[0] == null. Array.has(value) checks if a value is present, not if something exists at an index; this behavior is the opposite of Dictionary.has(key).

Solution

GDScript Arrays have a set size. If index is greater than or equal to the Array’s current size(), it will throw an error. To check if an arbitrary index is null/unset, use if index >= arr.size() or arr[index] == null. Likewise, if you want to set an array index that’s larger than the current size(), you’ll need to resize() the array to be larger (although this probably isn’t performant if done naively/often).

You might want to consider a Dictionary instead; I’m not totally sure of the space/time tradeoffs.

2

You can also use append() and erase() on a GDScript array to safely change the size of an array if you know what value you want to add or remove. But I agree that a Dictionary seems to fit your use case better of trying to find a value at a specific location (key).