Naming tables automatically in a function

function domeQuadrantTables(rad)
--make a table for each layer of quarter dome with x, y coordinates. x, y, and z are positive.
for j = 0, rad do
  if j < round(math.sqrt((rad^2)/3)) then
   for i = 0, round(math.sqrt(rad^2/2)) do
    z = j
    y = i
    x = round(math.sqrt(rad^2 - y^2 - z^2))
    if y >= x then
	 limit = y
	 for i = limit, 0, -1 do
	  z = j
	  x = i
	  y = round(math.sqrt(rad^2 - x^2 - z^2))
	  xy = x .. "," .. y
	  tablename = "ztable" .. z
	  tablename = {}
	  table.insert(tablename, xy)
	 end
	 break
    end
    xy = x .. "," .. y
    tablename = "ztable" .. z
    tablename = {}
    table.insert(tablename, xy)
   end
  else
   for x = round(math.sqrt((2 * rad^2)/3)), 0, -1 do
    for y = 0, round(math.sqrt((2 * rad^2)/3)) do
	 z = round(math.sqrt(rad^2 - x^2 - y^2))
	 if z == j then
	  xy = x .. "," .. y
	  tablename = "ztable" .. z
	  tablename = {}
	  table.insert(tablename, xy)
	 end
    end
   end 
  end
end
end
function buildFromTable(rad)
--Reads ztables and builds a quarter dome according to coordinates, layer by layer, bottom up.
--To make a shpere there would be 1 loop for each quarter of a dome, 8 loops total.
--The sign of the x, y, z coordinates and the order of reading from ztables would be changed accordingly in each loop.
for j = 0, rad do
  tablename = "ztable" .. j
  print(tablename)
  for i = 1, table.maxn(tablename) do
   xy = tablename[i]
   local xytable = {}
   for part in string.gmatch(xy, "[^,]+") do
    table.insert(xytable, part)
   end
   x = tonumber(xytable[1])
   y = tonumber(xytable[2])
   z = j
   navigateToZ(x, y, z)
   placeBlock()
   table.remove(xytable[1])
   table.remove(xytable[2])
  end
end
end

for i = 1, x do
  multiTable = {i={}}
end

multiTable = setmetatable({}, {__index = function(self, key) return {} end})

Symmetryc, on 08 June 2013 - 02:21 PM said:

I think this is what you're looking for:

multiTable = setmetatable({}, {__index = function(self, key) return {} end})

It makes every single index of "multiTable" automatically a table, no matter what number it is or key.

local maintable = {}
for i = 1, 5 do
   maintable[#maintable + 1] = {}
end

--[[
#<table-name> returns the length of the table. When we do +1, we create a new index and set the value to a new table. 

Essentially we are doing this:
local maintable = {
  [1] = {};
  [2] = {};
  [3] = {};
  [4] = {};
  [5] = {};
}
If you really wanted, you can overwrite indexes or create them:
for i = 1, 5 do
   maintable[i] = {}
end
]]

Engineer, on 08 June 2013 - 03:21 PM said:

Symmetryc, on 08 June 2013 - 02:21 PM said:

I think this is what you're looking for:

multiTable = setmetatable({}, {__index = function(self, key) return {} end})

It makes every single index of "multiTable" automatically a table, no matter what number it is or key.

It can be done waaay easier. You are deep into metatables, arent you?
Here for example:

local maintable = {}
for i = 1, 5 do
   maintable[#maintable + 1] = {}
end

--[[
#<table-name> returns the length of the table. When we do +1, we create a new index and set the value to a new table. 

Essentially we are doing this:
local maintable = {
  [1] = {};
  [2] = {};
  [3] = {};
  [4] = {};
  [5] = {};
}
If you really wanted, you can overwrite indexes or create them:
for i = 1, 5 do
   maintable[i] = {}
end
]]

local name = "variable"
_G[name] = 42
print(variable) -- prints 42

Symmetryc, on 08 June 2013 - 06:04 PM said:

I don't really see how this is easier, mine is one line of code that affects all indices, yours is multiple lines of code that only affects a limited amount of indices.

Symmetryc, on 08 June 2013 - 06:04 PM said:

Also, instead of thing[#thing+1]={} you can do table.insert(thing, {})

Orwell, on 08 June 2013 - 09:11 PM said:

If in the future you really want to give variables arbitrary names, you can do:

local name = "variable"
_G[name] = 42
print(variable) -- prints 42

This is usually not a good idea though (and indeed not what you need here).

local n = 'name'
getfenv()[ n ] = { 'test' }
print( name[1] )

Bomb Bloke, on 08 June 2013 - 10:29 PM said:

Symmetryc, on 08 June 2013 - 06:04 PM said:

I don't really see how this is easier, mine is one line of code that affects all indices, yours is multiple lines of code that only affects a limited amount of indices.

The catch is your method ALWAYS affects all indexes. So as soon as you try to pull stuff out of those tables it makes, it instead returns yet another fresh, empty table… That is to say, although all indexes act as tables, you can't store anything in them.

I like the idea behind it, though I'm not entirely sure I understand how it works. Best I can make out (without actually going off and looking up what metatables are), every time you try to refer to an index from the table it instead runs that function, so there's no way to have it actually KEEP those tables it's churning out without it inserting them into another table somewhere (if they're not already in there - you'd need to check for that) and then returning a pointer to the relevant one.

Symmetryc, on 08 June 2013 - 06:04 PM said:

Also, instead of thing[#thing+1]={} you can do table.insert(thing, {})

For what little it's worth, table.insert executes just a little bit more slowly. Or a lot more slowly, depending on your implementation.

local t = setmetatable({}, {__index = function()
return setmetatable({}, {__newindex = function(self, key, value) self[key] = value end})
end})

CountJankula, on 08 June 2013 - 01:45 PM said:

Ok, I think I get that.
How would I initialize a table so that the values of that table are themselves tables? And do it for some arbitrary number of indexes?

for i = 1, x do
  multiTable = {i={}}
end

doesn't seem like it would work

local multiTable = {}
for i = 1, 4 do
    table.insert(multiTable, {})
end

local multiTable = {}
for i=1, 4 do
  multiTable[i] = {}
end

Lyqyd, on 09 June 2013 - 05:08 AM said:

CountJankula, on 08 June 2013 - 01:45 PM said:

Ok, I think I get that.
How would I initialize a table so that the values of that table are themselves tables? And do it for some arbitrary number of indexes?

for i = 1, x do
  multiTable = {i={}}
end

doesn't seem like it would work

That's sort of what you want to do:

local multiTable = {}
for i = 1, 4 do
    table.insert(multiTable, {})
end

You then have a table of tables indexed from multiTable[1] through multiTable[4]. This will be much easier than all of the stuff they're talking about above.

Guys, if you want to have a discussion of metatables, please take it elsewhere. It's orthogonal to this question, and it's really not helping to have that discussion in this topic.

mZt = {}
for i = 1, 5 do
  table.insert(mZt, {})  --lyqyd
end

mZt = {}
for i = 1, 5 do
  mZt[#mZt + 1] = {} --Engineer
end

mZt = {
  [1] = {};
  [2] = {};
  [3] = {};
  [4] = {};
  [5] = {};
}

for j = 0, 5 do
  for i = 0, round(math.sqrt(5^2/2)) do
   z = j
   y = i
   x = round(math.sqrt(5^2 - y^2 - z^2))
   data = x .. "," .. y
   index = j + 1
   table.insert(mZt, index, data)
  end
end

print(mZt[1][1])
print(mZt[1][2])
print(mZt[1][3])

5,0
5,1
5,2

local tArgs = {...}
local rad = tArgs[1]
function round(num)
if num >= 0 then
  return math.floor(num+.5)
else
  return math.ceil(num-.5)
end
end
function domeQuadrantTables(rad)
--make a table for each layer (z axis) of a quarter of a dome with an ordered set of x, y coordinates. x, y, and z are positive.
mZt = {}
for i = 0, rad do
  --mZt[i] = {}   --Enginner and Kingdaro
  --mZt[#mZt + 1] = {} --Enginner
  table.insert(mZt, {})  --lyqyd
end
for j = 0, rad do
  if j < round(math.sqrt((rad^2)/3)) then
   for i = 0, round(math.sqrt(rad^2/2)) do
	z = j
	y = i
	x = round(math.sqrt(rad^2 - y^2 - z^2))
	if y >= x then
	 for i = y-1, 0, -1 do
	  z = j
	  x = i
	  y = round(math.sqrt(rad^2 - x^2 - z^2))
	  xy = x .. "," .. y
	  index = j + 1
	  table.insert(mZt, index, xy)
	 end
	 break
	end
	xy = x .. "," .. y
	index = j + 1
	table.insert(mZt, index, xy)
   end
  else
   for x = round(math.sqrt((2 * rad^2)/3)), 0, -1 do
	for y = 0, round(math.sqrt((2 * rad^2)/3)) do
	 z = round(math.sqrt(rad^2 - x^2 - y^2))
	 if z == j then
	  xy = x .. "," .. y
	  index = j + 1
	  table.insert(mZt, index, xy)
	 end
	end
   end
  end
end
end