# How to pick a weighted random element from an array in GDScript

Here’s an easy-to-use pick weighted random element from an array function in GDScript.

The colons (`:`

) mean that the variables infer their type from the context instead of typing them explicitly, e.g. `var msg: String = "hello"`

is the same as `var msg := "hello"`

. It does not affect the usage. The double hashtags are documentation comments.

```
## Returns a weighted random value from the target array using the second argument as the weights. Prints an error and returns null if the array is empty.
func weighted_pick_random(array: Array, weights: Array):
assert(array.size() == weights.size(), "The arrays must be of the same size")
if array.is_empty():
push_error("Tried picking a weighted random value from an empty array")
return null
var sum := 0.0
for num in weights:
sum += num
var rand := randf_range(0, sum)
var cumulative := 0.0
for i in array.size():
cumulative += weights[i]
if rand <= cumulative:
return array[i]
```

You can use the function like this:

```
func _ready():
var vals := [
"a",
"b",
"c",
]
var weights := [
1,
10,
5,
]
var value = weighted_pick_random(vals, weights)
```