Random but no duplicates?

SteveZX81

This post is deleted!

PB____

I don't think this is an elegant solution at all, and I haven't tested it. (I'm a bit tired but couldn't help having a throw at it)
But I think something like this should work:

function place(position)
	// your placing logic, where position is a vector.
return void

var positions = []
// build up an array with vectors of all the possible positions:
for x = 0 to 7 loop
	for y = 0 to 8 loop
		positions[len(positions)] = {x, y}
	repeat
repeat
int count = len(positions)
int amountToPlace = 4 // if you want to place 4 sprites
for i = 0 to amountToPlace loop
	int next = random(count)
	place(positions[next])
        // replace the used position with the next ones (you could also use a splice function for this, to keep the positions array clean at the end)
	while next < count - 1 loop
		positions[next] = positions[next + 1]
		next += 1
	repeat
	count -= 1
repeat

Hope it helps.

Martin

i think that can probably be simplified a little? But certainly along the same track... For this I'll assume you want to position 10 'things' in random, non duplicate places. I'm also not at my switch so I'll do 'pretend code and let you fill in the gaps / fix any anomolies'

array things[]
for n = 0 to 10 loop
    someVal = { random(maxX), random(maxY) }
    while isDuplicate(someVal) loop
        someVal = { random(maxX), random(maxY) }
    repeat
repeat

function isDuplicate(newVal)
    int result = false
    int n = 0
    for n = 0 to len(things) loop
        if newVal == things[n] then 
            result = true
            break
        endif
    repeat
return result

At the end of that code you should if all goes well have an array of 10 random but not duplicate positions?

SteveZX81

Thanks. I can't get that code to work without erroring but I suspect the fault is mine, I shall keep trying.

PickleCatStars

Make a 7x8 array, all filled with 0s, and mark the position as 1 if you use it. You can use that to see if a position is already filled.

tony7059

I've done something like this before... different, but similar. I wanted to randomize the positions of consecutive numbers to shuffle them. I think I randomly selected the number for the 1 spot. The random number was based on the max number of array indices. I moved that value at that location to the 1st spot. Then, I shift things in the choice array then, reduce the range of my random call to match the decrease of available indices. So I never had to check for duplicates, because I knew I had a clean number and position to place it in within the shuffled array. It's some extra work to shift items, but if this is an infrequent bit of processing it's no biggy. I needed to do this at the start/restart of a puzzle game I did in another language, but the same principle exists in Fuze.