Going through complex tables

[Ertain]

Hello again, everyone.

I have this little function which checks for collision. What I have to do, though, is first navigate through the large table that houses the numbers for my enemies. The table looks something like this (note: this isn't my real code; it's just for this example):

Code: Select all

group.enemy = {}
group.enemy[1] = {x = 20, y = 20, radius = 16, hasBeenHit = false}
group.enemy[2] = {
buzzard1 = { x = 20, y = 20, radius = 21, hasBeenHit = false}
buzzard2 = {x = 40, y = 40, radius = 21, hasBeenHit = false}
buzzard3 = {x = 60, y = 60, radius = 21, hasBeenHit = false}
}
group.enemy[3] = {
guy1 = {x = 20, y = 30, radius = 22, hasBeenHit = false}
guy2 = { x = 40, y = 70, radius = 22, hasBeenHit = false}
}

What I'm trying to do is go through each of the internal arrays to get to the right variable (in this case, the "x" and "y" variables). I can't figure out exactly how to do this because I can't exactly formulate the correct "for" statements to get it right. I thought of first using the ipairs() function to go through each element, but I still have to check for "x" and possibly go deeper (such as with the "buzzard" tables).

[Robin]

What makes it harder for yourself that some entries in the enemy table are 'entities', while others are collections of 'entities'.

You could try something like this:

Code: Select all

for i,e in ipairs(enemy) do
    if e.x then
        processenemy(e)
    else
        for k,v in pairs(e) do -- iterate over subtable
            processenemy(v)
        end
    end
end

[thelinx]

Code: Select all

for id, enemygroup in ipairs(group.enemy) do -- loop in the enemy.group table, giving each item to the scope as "enemygroup"
  for enemy_id, enemy in pairs(enemygroup) do -- loop in the enemy.group[n] table, giving each item to the scope as "enemy"
    print(enemy.x, enemy.y) -- refer to the variables as enemy.whatever
  end
end

I hope that helps!

[zac352]

I think he means he has nested tables. (I'm going to post an example of how to do that just in case:)

Code: Select all

function recursive(t)
    for k,v in pairs(t) do
        doSomething(t,k,v)
    end
end
recursive(someNestedTable)

[Robin]

I think he means he has nested tables. (I'm going to post an example of how to do that just in case:)

Code: Select all

function recursive(t)
    for k,v in pairs(t) do
        doSomething(t,k,v)
    end
end
recursive(someNestedTable)

That's not recursive at all.

[zac352]

I think he means he has nested tables. (I'm going to post an example of how to do that just in case:)

Code: Select all

function recursive(t)
    for k,v in pairs(t) do
        doSomething(t,k,v)
    end
end
recursive(someNestedTable)

That's not recursive at all.

Wait... Eh. I changed the name of my recursive function in the middle of writing it.

[Robin]

You mean

Code: Select all

function recursive(t)
   for k,v in pairs(t) do
        recursive(t,k,v)
    end
end
recursive(someNestedTable)

?
Then it would just be a fork bomb. (Unless the table passed is empty.)

[Ertain]

Thanks for the help, guys. Now all I need to do is figure out variable type (determining if a variable is a number, table, etc.).

[nevon]

Now all I need to do is figure out variable type (determining if a variable is a number, table, etc.).

You can use the type() function.

[zac352]

You mean

Code: Select all

function recursive(t)
   for k,v in pairs(t) do
        recursive(t,k,v)
    end
end
recursive(someNestedTable)

?
Then it would just be a fork bomb. (Unless the table passed is empty.)

I give up. I wrote that at 7:30 AM, not my brightest time of day.

Now all I need to do is figure out variable type (determining if a variable is a number, table, etc.).

You can use the type() function.

It'd be nice if you actually gave him some information on the type function...

Code: Select all

local a,b,c,d,e,f,g=42,"lol",{},io.open("Blargh.txt","w"),coroutine.create(function() end),function() end,g
print(type(a))
print(type(b))
print(type(c))
print(type(d))
print(type(e))
print(type(f))
print(type(g))

->number
->string
->table
->file
->thread
->function
->nil

Note: That last one is a string containing "nil", and not nil itself.