Displaying Lua tables to console by concatenating to string - lua

I was wondering whether it is possible to display tables in the console. Something like:
player[1] = {}
player[1].Name = { "Comp_uter15776", "maciozo" }
InputConsole("msg Player names are: " .. player[1].Name)
However, this is obviously wrong as I receive the error about it not being able to concatenate a table value. Is there a workaround for this?
Much thanks in advance!

To turn an array-like table into a string, use table.concat:
InputConsole("msg Player names are: " .. table.concat(player[1].Name, " "))
The second argument is the string placed between each element; it defaults to "".

to make life easier on yourself for this... i'd recommend naming elements in the inner tables as well. this makes the code above easier to read when you need to get at specific values in a table that are meaningful for some purpose.
-- this will return a new instance of a 'player' table each time you call it.
-- if you need to add or remove attributes, you only need to do it in one place.
function getPlayerTable()
return {FirstName = "", LastName = ""}
end
local players = {}
local player = getPlayerTable()
player.FirstName = "Comp_uter15776"
player.LastName = "maciozo"
table.insert(players, player)
... more code to add players ...
local specific_player = players[1]
local specific_playerName = specific_player.FirstName..
" ".. specific_player.LastName
InputConsole("msg Some message ".. specific_playerName)

Related

Lua: Passing index of nested tables as function arguments?

Is it possible to have a function that can access arbitrarily nested entries of a table?
The following example is just for one table. But in my real application I need the function to check several different tables for the given (nested) index.
local table1 = {
value1 = "test1",
subtable1 = {
subvalue1 = "subvalue1",
},
}
local function myAccess(index)
return table1[index]
end
-- This is fine:
print (myAccess("value1"))
-- But how do I access subtable1.subvalue1?
print (myAccess("subtable1.subvalue1???"))
You won't be able to do this using a string unless you use load to treat it as Lua code or make a function to walk on a table.
You can make a function which will split your string by . to get each key and then go one by one.
You can do this using gmatch + one local above gmatch with current table.
#Spar: Is this what you were suggesting? It works anyway, so thanks!
local table1 = {
value1 = "test1",
subtable1 = {
subvalue1 = "subvalue1",
},
}
local function myAccess(index)
local returnValue = table1
for key in string.gmatch(index, "[^.]+") do
if returnValue[key] then
returnValue = returnValue[key]
else
return nil
end
end
return returnValue
end
-- This is fine:
print (myAccess("value1"))
-- So is this:
print (myAccess("subtable1.subvalue1"))

lua: user input to reference table

I am having trouble with my tables, I am making a text adventure in lua
local locxy = {}
locxy[1] = {}
locxy[1][1] = {}
locxy[1][1]["locdesc"] = "dungeon cell"
locxy[1][1]["items"] = {"nothing"}
locxy[1][1]["monsters"] = {monster1}
The [1][1] refers to x,y coordinates and using a move command I can successfully move into different rooms and receive the description of said room.
Items and monsters are nested tables since multiple items can be held there (each with their own properties).
The problem I am having is getting the items/monsters part to work. I have a separate table such as:
local monsters = {}
monsters["rat"] = {}
monsters["rat"]["Name"] = "a rat"
monsters["rat"]["Health"] = 5
monsters["rat"]["Attack"] = 1
I am using a table like this to create outlines for various enemy types. The monster1 is a variable I can insert into the location table to call upon one of these outlines, however I don't know how to reference it.
print("You are in ", locxy[x][y]["locdesc"]) -- this works
print("You can see a ", locxy[x][y]["monsters]["Name"],".") - does not work
So I would like to know how I can get that to work, I may need a different approach which is fine since I am learning. But I would also specifically like to know how to / if it possible to use a variable within a table entry that points to data in a separate table.
Thanks for any help that can be offered!
This line
locxy[x][y]["monsters]["Name"]
says
look in the locxy table for the x field
then look in the y field of that value
look in the "monsters"` field of that value
then look in the "Name" field of that value
The problem is that the table you get back from locxy[x][y]["monsters"] doesn't have a "Name" field. It has some number of entries in numerical indices.
locxy[x][y]["monsters][1]["Name"] will get you the name of the first monster in that table but you will need to loop over the monsters table to get all of them.
Style notes:
Instead of:
tab = {}
tab[1] = {}
tab[1][1] = {}
you can just use:
tab = {
[1] = {
{}
}
}
and instead of:
monsters = {}
monsters["rat"] = {}
monsters["rat"]["Name"] = "foo"
you can just use:
monsters = {
rat = {
Name = "foo"
}
}
Or ["rat"] and ["Name"] if you want to be explicit in your keys.
Similarly instead of monsters["rat"]["Name"] you can use monsters.rat.Name.

Create a numerical table from the values of a non numerical table

Backpack = {Potion = 'backpack',Stack = 'bag',Loot = 'derp', Gold = 'random'}
Backpack[1] ~= 'backpack' -- nope
As you guys can see, I cannot call Backpack[1] since its not a numeral table, how would I generate a table after the construction of Backpack, consisting only of it's values? for example:
Table_to_be_Constructed = {Value of Potion,Value of Stack,Value of Loot,Value of Gold} -- this is what i need
It seems simple but I couldn't find a way to do it.
I need it this way because i will run a numeric loop on Table_to_be_Constructed[i]
To iterate over all the key-value pairs in a table, use the pairs function:
local Table_to_be_Constructed = {}
for key, value in pairs(Backpack) do
table.insert(Table_to_be_Constructed, value)
end
Note: the iteration order is not defined. So, you might want to sort Table_to_be_Constructed afterwards.
By convention, the variable name _ is used to indicate a variable who's value won't be used. So, since you want only the values in the tables, you might write the loop this way instead:
for _, value in pairs(Backpack) do
For the updated question
Backpack has no order (The order in the constructor statement is not preserved.) If you want to add an order to its values when constructing Table_to_be_Constructed, you can do it directly like this:
local Table_to_be_Constructed = {
Backpack.Potion,
Backpack.Stack,
Backpack.Loot,
Backpack.Gold
}
Or indirectly like this:
local items = { 'Potion', 'Stack', 'Loot', 'Gold' }
local Table_to_be_Constructed = {}
for i=1, #items do
Table_to_be_Constructed[i] = Backpack[items[i]]
end

Inserting Key Pairs into Lua table

Just picking upon Lua and trying to figure out how to construct tables.
I have done a search and found information on table.insert but all the examples I have found seem to assume I only want numeric indices while what I want to do is add key pairs.
So, I wonder if this is valid?
my_table = {}
my_table.insert(key = "Table Key", val = "Table Value")
This would be done in a loop and I need to be able to access the contents later in:
for k, v in pairs(my_table) do
...
end
Thanks
There are essentially two ways to create tables and fill them with data.
First is to create and fill the table at once using a table constructor. This is done like follows:
tab = {
keyone = "first value", -- this will be available as tab.keyone or tab["keyone"]
["keytwo"] = "second value", -- this uses the full syntax
}
When you do not know what values you want there beforehand, you can first create the table using {} and then fill it using the [] operator:
tab = {}
tab["somekey"] = "some value" -- these two lines ...
tab.somekey = "some value" -- ... are equivalent
Note that you can use the second (dot) syntax sugar only if the key is a string respecting the "identifier" rules - i.e. starts with a letter or underscore and contains only letters, numbers and underscore.
P.S.: Of course you can combine the two ways: create a table with the table constructor and then fill the rest using the [] operator:
tab = { type = 'list' }
tab.key1 = 'value one'
tab['key2'] = 'value two'
Appears this should be the answer:
my_table = {}
Key = "Table Key"
-- my_table.Key = "Table Value"
my_table[Key] = "Table Value"
Did the job for me.

how do i iterate the tables parameters which is present under the main table?

In lua ,im calling a function which returns a table variable that contains many parameter internally..but when i get that value i couldnt access the paramter which is present in the table. I can see the tables parameter in the original function in the form of
[[table:0x0989]]
{
[[table:0x23456]]
str = "hello"
width = 180
},
[[table:0x23489]]
{
str1 = "world"
}
it shows like this.but when it returns once i can able to get the top address of table like [[table:0x0989]]..when i tried acessing the tables which is present inside the main table.it is showing a nil value...how do i call that ?? can anyone help me??
If I'm reading it correctly you're doing this:
function my_function ()
--do something
return ({a=1, b=2, c=3})
end
From that you should be able to do this:
my_table = my_function()
then
print(my_table.a) --=> 1
print(my_table.b) --=> 2
print(my_table.c) --=> 3

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