CODEWITHSUNDEEP
luacoronasdk
Gooner
Gooner

Reputation: 387

Corona table.sort()

local tile = {"C", "O", "L", "I", "N", "F", "A", "R", "R", "E", "L", "L"}       
table.sort(tile, function(a,b) return ( math.random(1,2) <2) end)
print ( 'table: '..table.concat( tile, ', '))

I am randomizing the order of the table, which seems to work fine, but every 2nd time I run the program I get this error : invalid order function for sorting. Any suggestions as to what is happening?

I have found the solution to this. http://developer.coronalabs.com/code/shufflerandomize-tables This will shuffle the contents of your table without any of the problems of the method above.

Upvotes: 3

Views: 1279

Answers (2)

Michal Kottman
Michal Kottman

Reputation: 16753

If you want to shuffle an array, take a look at my shuffle snippet.

The main idea is that you create a table of items with random numbers, sort that while keeping the original index, and reorder the items according to the new order.

function shuffled(tab)
    local n, order, res = #tab, {}, {}
    for i=1,n do order[i] = { rnd = math.random(), idx = i } end
    table.sort(order, function(a,b) return a.rnd < b.rnd end)
    for i=1,n do res[i] = tab[order[i].idx] end
    return res
end

Upvotes: 4

lhf
lhf

Reputation: 72312

The sort function given to table.sort is assumed to be deterministic in the sense that it always returns the same result for the same pair of arguments, and consistent, in the sense that a<b and b<c implies a<c.

Upvotes: 1

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