Table indexes

[Drakath]

I have a problem with table indexes.

I used: #myTable to check how much players are in the table, however it always outputted 0 even though I did put some players in the table.

table.maxn(myTable) showed a number higher than 0, however when I did table.random(myTable), it outputted:

bad argument #1 to 'random' (interval is empty)

This is how I put players into table (Server-side):

     local myTable= {} 
    for index,player in ipairs(getElementsByType("player")) do 
     if getDistanceBetweenPoints3D(Px,Py,Pz,x,y,z) < 100 then 
        myTable[index] = player 
                outputChatBox("Success") 
 end  
end 

It does output success but #myTable is 0. Can someone explain why?

[ZL|LuCaS]

I have a problem with table indexes.

I used: #myTable to check how much players are in the table, however it always outputted 0 even though I did put some players in the table.

table.maxn(myTable) showed a number higher than 0, however when I did table.random(myTable), it outputted:

bad argument #1 to 'random' (interval is empty)

This is how I put players into table (Server-side):

local myTable= {}  
for index,player in ipairs(getElementsByType("player")) do 
     if getDistanceBetweenPoints3D(Px,Py,Pz,x,y,z) < 100 then 
        myTable[index] = player 
                outputChatBox("Success") 
 end  
end 

It does output success but #myTable is 0. Can someone explain why?

you need to check line 3 --getDistanceBetweenPoints3D

 local myTable= {} 
    for index,player in ipairs(getElementsByType("player")) do 
    -- if getDistanceBetweenPoints3D(Px,Py,Pz,x,y,z) < 100 then 
        myTable[index] = player 
                outputChatBox(#myTable) 
 --end 
end 

returns players !

[Drakath]

No, I need to only return players which are near another object I stated.

[ZL|LuCaS]

No, I need to only return players which are near another object I stated.

  
local x,y,z= getElementPosition ( localPlayer ) 
aa = createPed(0,x,y,z) 
  
  
 local myTable= {} 
 local x,y,z= getElementPosition ( aa ) 
    for index,player in ipairs(getElementsByType("player")) do 
     local a,b,c = getElementPosition ( player ) 
        local distance = getDistanceBetweenPoints3D(x,y,z,a,b,c) 
        if distance and (distance < 100) then 
        myTable[index] = player 
                outputChatBox(#myTable) 
 end 
end 

[DiSaMe]

# operator returns the index before the first index with a nil value. That is, table[#table+1] is nil. So if you don't put all values starting at index 1 and incrementing by 1, # returns the index before the first gap. For example, if you set values at indices 1, 2, 6, 8, 9, then # will return 2 because table[3] is nil.

[Drakath]

I see but I can't figure out how to make a work around for this. If I use table.maxn, it returns the right number but table.random doesn't work. Any help with the code would be appreciated.

[Saml1er]

You can do this with meta methods ( __index and _newindex)

Check ixjf post.

viewtopic.php?f=91&t=80425

If you use that code then when ever you get the length of table using # it will return __n and if you see carefully you will find another table __data where all of your data is kept.

For more metatable events: http://lua-users.org/wiki/MetatableEvents

[Drakath]

Ahh, I can't get it to work. Getting the total number isn't hard but how can I make it work with table.random

function table.random ( theTable )      
return theTable[math.random ( #theTable )]  
end 

[Anubhav]

  
function table.random ( theTable )     
return theTable[ math.random ( 1, #theTable ) ] 
end 
  

[Drakath]

Lol, it won't work. Didn't you read what CrystalMV posted?

[Saml1er]

You got this wrong.

  
local __n = 5-- suppose table size is 5 but your table has 1,3,5,9,10 indexes 
local ran = math.random (__n) -- but this will return number between 1-5 it can also be 2 or 4 which is not your table index 
  

There's no possible way to do this other than a loop but we'll optimize the code by using a single loop rather than using 2.

I found something useful on a forum. I modified his code a little. Here,

Post by Robin:

Also, a better way of dealing this is to keep another list with the keys:

Code:

  
local function generate_key_list(t) 
    local keys = {} 
    for k, v in pairs(t) do 
        keys[#keys+1] = k 
    end 
    return keys 
end 
  

then you can do:

Code:

  
local keys = generate_key_list(myTable) 
local randomValue = myTable[keys[math.random(#keys)]]  
  

[Drakath]

if table.maxn(myTable) > 0 then  
local keys = generate_key_list(myTable) 
local random = myTable[keys[math.random(#keys)]] 
outputChatBox(random) 
end 
  

I'm going to test it now but I have a couple of questions.

1. Is table.maxn okay to see if there are any players in the table?

2. If I use this client-side triggered by server, would every client receive an output of a different player or the same player?

[Saml1er]

1. Yes.

2. They will get different output since math.random exists for this purpose.

[Drakath]

Seems to work fine. Thank you

[Saml1er]

You're welcome.

[ixjf]

Simply replace "myTable[index] = player" with "table.insert ( myTable, player )" in your original code and get rid of all the crap you've been told to do.

Edited October 19, 2014 by Guest

[Saml1er]

Simply replace "myTable[index] = player" by "table.insert ( myTable, player )" in your original code and get rid of all the crap you've been told to do.

I think I completely misunderstood him. Your code makes complete sense since table.insert will take care of index [#myTable+1] = v. Btw whatever I wrotr was for string keys. If you're using index keys then do what ixjf said.

[IIYAMA]

To be honest the table.insert has it's benefits, but not in this code.

Table.insert is a little bit slower(because it is a function), so you won't have benefit from it now.

Benefit of table.insert is that you can add data at fields without overwrite other fields.

myTable = { 
"hi1","hi2","hi4" 
} 
table.insert(myTable,3,"hi3" ) 
  
outputChatBox = outputChatBox or print  
for i=1,#myTable do 
outputChatBox(myTable[i]) 
end 

Result:

hi1 
hi2 
hi3 
hi4 

So do what you want to use and know the differences between them!