You can see the calculations. Every element would need to be set to a variable, and then the outcome would need to be set to a variable. Then you put all of them into a ds_list add call, or whatever. Like this (I'm using a for loop for the example here, but it wouldn't really be different in practice with a while loop):
for (a = 0; a < 1000; a++)
{var length_left = 50 * a;
var dir = 10 * a;
var left_x = x + lengthdir_x(length_left, dir);
var left_y = y + lengthdir_y(length_left, dir);
ds_list_add(list, a, length_left, dir, left_x, left_y} // etc etc
Whatever you want to know - set a variable to it, so it can be accessed. And if it can be accessed it can be put into whatever you want to store it, and then be drawn onscreen by looping through the storage.