CODEWITHSUNDEEP
arraysindexinglua
Chase
Chase

Reputation: 59

Return index of an array of tables

I have the array:

racers = {}
racers[6] = {plCP = 4, plID= 21}

If I have the value plID=21, is there a way to return the index of racers? (In this case I'd like to return 6.)

I tried building a reverse index, but I'm only really able to get indexes within the table. Here's what I'm trying right now:

local index={}
for i = 1,5 do
    for k,v in pairs(racers[i]) do
       index[v]=k
    end
end

This returns "plID" when I pass the value 21, but I'd like it to return 6.

Upvotes: 1

Views: 39

Answers (2)

Piglet
Piglet

Reputation: 28958

For every racer in your list check wether the plID equals the id you are looking for.

local racers = {}
racers[1] = {plCP = 4, plID= 21}
racers[2] = {plCP = 2, plID= 4}
racers[3] = {plCP = 6, plID= 5}
racers[4] = {plCP = 222, plID= 7}
racers[5] = {plCP = 6, plID= 12}

function getRacerIndexById(racerList, id)
      for index, racer in ipairs(racerList) do
        if racer.plID == id then
          return index
        end
      end
    end

print(getRacerIndexById(racers, 12))

Upvotes: 1

Chase
Chase

Reputation: 59

Figured it out.

racers = {}
racers[1] = {plCP = 4, plID= 21}
racers[2] = {plCP = 2, plID= 4}
racers[3] = {plCP = 6, plID= 5}
racers[4] = {plCP = 222, plID= 7}
racers[5] = {plCP = 6, plID= 12}

local index={}
for i,d in pairs(racers) do
for k,v in pairs(racers[i]) do
   index[v]=i
end
end

return index[12]

This returns 5, which is the index of racers I was looking for.

Upvotes: 0

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