Lua find a key from a value

Question

I'm working with this:

chars = {
    ["Nigo Astran"] = "1",
    ["pantera"] = "2"
}
    
nchar = chars[$name] + 1

The variable $name will give me a string that I'm logged in to, in this case: "Nigo Astran" and nchar has the value "2" if I'm in "Nigo Astran", and so on. I believe you get the idea.

Now, I want to get the key from the value, for example:

when nchar is "2" it should give me "pantera" as the key. I'm just not getting the value of the key.

Answer 1

If you find yourself needing to get the key from the value of a table, consider inverting the table as in

function table_invert(t)
   local s={}
   for k,v in pairs(t) do
     s[v]=k
   end
   return s
end

Answer 2

I don't think there is anything more efficient than looping over the entries in the table using pairs and comparing the keys.

you can do that using something like this

function get_key_for_value( t, value )
  for k,v in pairs(t) do
    if v==value then return k end
  end
  return nil
end

Then you'd use it like this:

local k = get_key_for_value( chars, "1" )