A ds_grid is basically a type of two-dimensional array. You define the grid by setting its integer width and height, which then sets the total number of "cells" within the grid (the width and height multiplied) and these cells are then used to hold different data values (real numbers or strings).

This type of structure allows you to set and retrieve the value of cells in the grid by giving the x and y index of it (which starts with 0 for both the x and the y axis and goes up to the width - 1 and the height -1). But you can also set the value in specific grid regions, add single values, and retrieve the sum, maximum, minimum, and mean value over a given region, making this data structure the most versatile of all those available to you.

When accessing DS grid data structures, you should always try to use integer values for the cell position, and all non-integer indices will be floored by GameMaker Studio 2 if you do not. If that is not what you require, then you will need to do the rounding yourself previously before passing the index that you wish to check.

The following functions exist that deal with DS grids.

1. ds_grid_create
   
2. ds_grid_destroy
   
3. ds_grid_width
   
4. ds_grid_height
   
5. ds_grid_resize
   
6. ds_grid_clear
   
7. ds_grid_set
   
8. ds_grid_set_disk
   
9. ds_grid_set_grid_region
   
10. ds_grid_set_region
    
11. ds_grid_shuffle
    
12. ds_grid_sort
    
13. ds_grid_get
    
14. ds_grid_get_max
    
15. ds_grid_get_mean
    
16. ds_grid_get_min
    
17. ds_grid_get_sum
    
18. ds_grid_get_disk_max
    
19. ds_grid_get_disk_mean
    
20. ds_grid_get_disk_min
    
21. ds_grid_get_disk_sum
    
22. ds_grid_add
    
23. ds_grid_add_region
    
24. ds_grid_add_disk
    
25. ds_grid_add_grid_region
    
26. ds_grid_multiply
    
27. ds_grid_multiply_disk
    
28. ds_grid_multiply_region
    
29. ds_grid_multiply_grid_region
    
30. ds_grid_value_exists
    
31. ds_grid_value_disk_exists
    
32. ds_grid_value_x
    
33. ds_grid_value_y
    
34. ds_grid_value_disk_x
    
35. ds_grid_value_disk_y
    
36. ds_grid_copy
    
37. ds_grid_read
    
38. ds_grid_write
    

Apart from these specific functions you can all use an expression (called an accessor) to add or modify the contents of your ds_grid. This accessor looks similar to a 2D array with the following syntax:

grid_index[# xpos, ypos]

You can find more information, plus examples, from from the GML Overview page on Accessors.