+5 votes

I can create a 1-dimensional array as follows:

var list = []

How would I create a 2-dimensional array? I can't seem to find an obvious example in the docs or project examples. In Python I think it would be:

var matrix = [[0 for x in range(width)] for y in range(height)] 

but this returns an error in Godot.

in Engine by (101 points)

7 Answers

+5 votes
Best answer

godotscript is not python and doesn't follow the pythonic way. Simply do it the old fashion way:

var matrix=[]
for x in range(width):
    matrix[x]=[]
    for y in range(height):
        matrix[x][y]=0
by (703 points)
selected by

This approach is returning an error " Invalid set index '0' (on base: 'Array'). " at the first step

matrix[x] = []

Strange. I did try it yesterday. Anyway, maybe using

matrix.append([])

does the trick. The theory for the n dimensional matrix doesn't change.

Thank you , that seems to fix the problem:

var matrix = []
for x in range(width):
    matrix.append([])
    matrix[x]=[]        
    for y in range(height):
        matrix[x].append([])
        matrix[x][y]=0

Almost, I fixed it for you. Your method had some redundancies that slowed it down.

var matrix = []
for x in range(width):
    matrix.append([])
    for y in range(height):
        matrix[x].append(0)

matrix[x]=[]

this sets the [] you just appended into a []

matrix[x].append([])

matrix[x][y]=0

these append a [] and then set the [] to a 0, which is weird and inefficient

the cleaned up method simply starts with a [], then adds [] as rows, ex: [ [],[],[] ]
then adds 0's into the rows, ex: [ [0,0,0],[0,0,0],[0,0,0] ]

one last side note: if you are making a very large 2D array (300x300 or higher), it seems to be faster to use a while loop instead of the for each loop with the range method, because the range method does something along the lines of building an array, ex: range(3) makes an array = [0,1,2]. This is slower than simply having an increment counter, ex: int x = 0, while(x<3), x += 1

very helpful, thanks for the advice and improvements!

Use append_array() for arrays, efficient for it expects specifically an array.
Examples:

array1.append_array(array2)
+11 votes

Or such:

func create_map(w, h):
    var map = []

    for x in range(w):
        var col = []
        col.resize(h)
        map.append(col)

    return map

Return Null-filled array.

by (44 points)
+3 votes

This is the way I create 2d arrays in godot:

var array_a = [1,2,3,4]
var array_b = [5,6,7,8]

var array_2d = [array_a, array_b]

And then, to read:

array_2d[0,1] -> 2
array_2d[1,2] -> 7
by (20 points)

I believe the correct way to read/write is (now):

array_2d[0][1] -> 2 

etc...

At least that's what i experienced in Godot 3.0

+9 votes

Seeing these awful answers; this is the most performance-friendly way of creating it:

func create_2d_array(width, height, value):
    var a = []

    for y in range(height):
        a.append([])
        a[y].resize(width)

        for x in range(width):
            a[y][x] = value

    return a

To be used as array[y][x].

by (1,113 points)

This comment is ancient now, but why did you put y before x? That seems pretty programmer-unfriendly, considering that every other time coordinates are used, they go in alphabetical order (x,y)

@Davi-Danger, that isn't always true. It comes down to row-major vs. column major, which very much depends on the application of the 2D array. If I'm modeling something like a matrix, it isn't uncommon at all to have y first; and in some APIs it's the standard to do it that way.

After all, it doesn't just affect how the programmer sees it, it affects how it's arranged in memory.

2D Arrays are still not listed in documentation.

+1 vote
#creating 2D Arrays in GDscript
var my_array = [[]]

var width = 5
var height = 5

func _ready():
#setting 2D Array size
for x in width:
    my_array.resize(width)

    for y in height:
        my_array[x].resize(y)

#setting a value
my_array[0][0] = 1
by (16 points)
+1 vote

The simplest way is probably:

var r = [0,0,0,0,0,0,0,0,0,0,0,0,0]#r for row
var matrix = [r,r,r,r,r,r,r,r,r,r,r,r,r,r,r]
by (16 points)
0 votes

extends Node2D
var AilList = Array()
func _on
Buttonpressed():
$Label.text=str("hi")
Ail
List = make2darray()
print(AilList)
print(Ail
List[0][3])

func make2darray():
var array1 = Array()
var i
hei =[0,1 ,2 ,3 ,4, 5, 6 ,7 ,8 ,9 ,10 ,11 ,12 ,13 ,14 ,15 ,16]
var width = 4
var height = 4
var counok = 0
for i in width:
var array
2 = Array()
for j in height:
array2.append(ihei[counok])
coun
ok += 1
array1.append(array2)
return array_1

by (14 points)
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