Problem with looking for something in a ds list

[Ukaygee]

Hi, so I'm looking for a specific value within a map.

I tried ds_map_find_next, with the help of the manual, but that did not work.

I know with lists, there is ds_list_find_index, but I'm wondering if there is this sort of function for a map?

Anyone have any ideas?

 

[chamaeleon]

What did you do that is different from this (untested) code

var k = ds_map_find_first(mymap);
while (!is_undefined(k) && mymap[? k] != myvalue)
{
    k = ds_map_find_next(mymap, k);
}
if (!is_undefined(k))
{
    ... Do something with k
}

 

[PNelly]

What makes maps useful is that they eliminate the need for that kind of search, you can associate a value with a name, and then lookup that value by using the name when you need it.

// your character picks up a sword
ds_map_add(my_map, "sword_power", 100);

// your character picks up a different sword
ds_map_replace(my_map, "sword_power", 200);

// your character hits an enemy
damage = ds_map_find_value(my_map, "sword_power");

If you need to perform an iterative search through your data then a list or array would be the way to go. The approach @chamaeleon suggests will work (as in, produce correct results), but it's very inefficient. I've seen it slow to a frame-busting crawl for map sizes of just a few hundred elements.

 

[chamaeleon]

What makes maps useful is that they eliminate the need for that kind of search, you can associate a value with a name, and then lookup that value by using the name when you need it.

What @Ukaygee is looking for is the equivalent of ds_list_find_index, which in theory could have been named ds_map_find_key.. Since it's not there, code along what I wrote is necessary, or you could use two maps, with the caveat that keys can only be strings or integers and use something like below.

my_key_map[? k] = v;
my_value_map[? v] = k;

And then look up in either map depending on the specific need, and any updates made to one map would have to be carefully managed

ds_map_delete(my_value_map, my_key_map[? k]);
my_key_map[? k] = new_v;
my_value_map[? new_v] = k;

 

[Ukaygee]

@chamaeleon thanks, your solution worked.