Table Not In Order?

Hi everyone!

first of, here's my code (its not big, i'm testing many things):

local IDs = {Paper = {}, White_Ink = {}, Orange_Ink = {}}

function getIDs()
  local event, ID = os.pullEvent("isort_item")
  return ID
end

for i,j in pairs(IDs) do
  IDs[i] = getIDs()
  print(i.." "..IDs[i])
end

The point of this lines is to know IDs (think you understood it). But! it returns:

White_Ink 339
Paper 491871
Orange_Ink 459103

instead of (or, i want this)

Paper 339
White_Ink 491871
Orange_Ink 459103

Why does "White_Ink" come before "Paper"? Think i did a really little mistake but i don't find where ><

no you didn't make a mistake, pairs does not access elements in order unless they are numerically indexed values.

local t = {3,7,6}

for k,v in pairs(t) do
  print(k, ' = ', v)
end

the above code will output

1 = 3
2 = 7
3 = 6

however when dealing with key/value pairs it can be any order (however it is the same order each time)

local t = { key = "value", ["foo"] = "bar", hello = 5, world = 1 }

for k,v in pairs(t) do
  print(k, ' = ', v)
end

could output (since I've not ran the code)

world = 1
foo = bar
key = value
hello = 5

the only thing that we can be certain of is that indexes will be in order even with keys

local t = {1, key = "value", 6, foo = "bar", 8, 9 }

for k,v in pairs(t) do
  print(k, ' = ', v)
end

will output

1 = 1
2 = 6
3 = 8
4 = 9
foo = "bar"
key = "value"

there are always functions that you can make to make sure it comes out in the order you wish, but it requires having some kind of "order"/"rule" element, or wanting it in alphabetical order, or something like that, not something that seems fairly arbitrary.

Yeah, think i found the way to do what i want!

local IDs = {[1] = {"Paper"}, [2] = {"White_Ink"}, [3] = {"Orange_Ink"}}

function getIDs()
  local event, ID = os.pullEvent("isort_item")
  return ID
end

for i,j in pairs(IDs) do
  IDs[i][#IDs[i]+1] = getIDs()
  print(IDs[i][1].." "..IDs[i][2])  
end

This time it returns:



Your help + http://lua-users.org/wiki/TablesTutorial (in fact, your post helped me alot to understand the wiki ^^) = win for me!

thanks ;)/>

Neekow, on 23 November 2013 - 11:56 AM said:

Yeah, think i found the way to do what i want!

local IDs = {[1] = {"Paper"}, [2] = {"White_Ink"}, [3] = {"Orange_Ink"}}

function getIDs()
  local event, ID = os.pullEvent("isort_item")
  return ID
end

for i,j in pairs(IDs) do
  IDs[i][#IDs[i]+1] = getIDs()
  print(IDs[i][1].." "..IDs[i][2])  
end

-snip

you don't need to put the curly braces around your stings, that creates another table you can just have it like this

local IDs = {"Paper","White_Ink","Orange_Ink"}

Huh … but i want "Paper" as a table, to contain ID and Amount … do your thing works in this way? ^^

Have another question … still on tables …
I want to write the table on another file so did:

IDfile = fs.open("ID", "r")
IDfile.write(IDs)
IDfile.close()

Yeah ok, easy, it writes the whole table on the file, but how can i get it back as a table from another program?
Was thinking on IDs = IDfile.read(IDs) but doesn't work and others tests just return me the whole thing as a string … i'm pretty sure it's just a function (something like: totable()) … but don't find anything on that =/

… ok was really far far away of this page …
works perfectly, thanks guys =)