Convert a 1d array index to a 3d array index?

Question

I've got a int that I want to convert to 3 ints for the index of a 3d array, here's an example of what I'm on about.

byte[,,] array = new byte[XSize, YSize, ZSize];

int i = 0;

//other code

array[#,#,#] = cur;

//other code

I don't know how to get the correct numbers for the #,#,# from just i.

Could you provide more information? Are you trying to iterate over all items? Or are you attempting to directly access a single element from a single lookup value? — Jaime Torres
– Jaime Torres, Commented Jul 3, 2012 at 17:58
My previous comment still holds: Can you provide an input and the expected output? — Austin Salonen
– Austin Salonen, Commented Jul 3, 2012 at 17:59
I think you are trying to map (0,0,0) to 0, (0,0,1) to 1 and so on. Is that what you want? Could you clarify your question? — James
– James, Commented Jul 3, 2012 at 17:59
@Lost Its better to improve previous question rather than posting new question..... — Glory Raj
– Glory Raj, Commented Jul 3, 2012 at 18:01

BlackVegetable · Accepted Answer · 2012-07-03 18:06:08Z

17

Supposing you want to iterate through Z, then Y, and then X. . .

int zDirection = i % zLength;
int yDirection = (i / zLength) % yLength;
int xDirection = i / (yLength * zLength);

answered Jul 3, 2012 at 18:06

BlackVegetable

13.2k8 gold badges53 silver badges86 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

JamieSee · Accepted Answer · 2019-08-28 18:37:18Z

You have to make an assumption about the orientation of the array-space. Assuming you are mapping the numbers with 0 corresponding to 0, 0, 0, and that you iterate z, then y, then x, the math is fairly simple:

int x;
int y;
int z;

if (i < XSize * YSize * ZSize)
{
    int zQuotient = Math.DivRem(i, ZSize, out z);
    int yQuotient = Math.DivRem(zQuotient, YSize, out y);
    x = yQuotient % XSize;
}

Note that this saves some redundant operations over BlackVegetable's solution. For a (3, 3, 3) matrix, this yields the set:

i (x, y, z)
0 (0, 0, 0)
1 (0, 0, 1)
2 (0, 0, 2)
3 (0, 1, 0)
4 (0, 1, 1)
5 (0, 1, 2)
6 (0, 2, 0)
7 (0, 2, 1)
8 (0, 2, 2)
9 (1, 0, 0)
10 (1, 0, 1)
11 (1, 0, 2)
12 (1, 1, 0)
13 (1, 1, 1)
14 (1, 1, 2)
15 (1, 2, 0)
16 (1, 2, 1)
17 (1, 2, 2)
18 (2, 0, 0)
19 (2, 0, 1)
20 (2, 0, 2)
21 (2, 1, 0)
22 (2, 1, 1)
23 (2, 1, 2)
24 (2, 2, 0)
25 (2, 2, 1)
26 (2, 2, 2)

Also, this is reversible with i = z + y * ZSize + x * ZSize * YSize.

Collectives™ on Stack Overflow

Convert a 1d array index to a 3d array index?

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related