Help Selecting 3 Different Maps

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#1

So I’m trying to create a map voting system but I need to select 3 new and different maps to vote on each time. I need help working out the logic to select the 3 different maps from a folder every time I call a function.

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Any help is appreciated.

1 Like
#2

Create a list of the maps, shuffle it, and use the first three.

Or repeatedly pick a random index until you have three unique indices.

#3

How would I “shuffle” the list? EDIT: Used the random index method instead, thanks!

#4

For what it’s worth, a Fischer-Yates shuffle would work.

Edit: that answer actually looks like it changes the original table and makes a new one, which is dumb. I would just shuffle in place:

function FYShuffle( tInput )
    for i = #tInput, 2, -1 do
        local j = math.random(i)
        tInput[i], tInput[j] = tInput[j], tInput[i]
    end
end

local t = {1,2,3,4,5,6}

print(table.concat(t, ","))
-- 1,2,3,4,5,6

FYShuffle(t)

print(table.concat(t, ","))
-- 1,3,2,6,4,5
#5

Is there a less complex way of doing it? The method I tried didn’t actually work.

#6

Also I packed the other way (repeated random sampling until you get a new result) into an iterator:


local function random_n(t, n)
    local chosen = {}
    local num = 0
	return function()
        if num == n then return nil end
		local i
		repeat i = math.random(1, #t) until not chosen[i]
		chosen[i] = true
        num = num + 1
		return i, t[i]
	end
end

-- example usage

local t = {"a", "b", "c", "d", "e", "f"}

for i, v in random_n(t, 4) do
	print(i, v)
end

--[[
3	c
5	e
2	b
1	a
--]]

It’s not smart for large tables, but for something like this it would be fine.

Turning the shuffle-and-choose method into an iterator is left as an exercise for the reader :slight_smile: