Lua find a key from a value

Question

I\'m working with this:

    chars = {
         [\"Nigo Astran\"]=\"1\",
         [\"pantera\"]=\"2\"
         }

   nchar = (chars[$name])+1

<

Answer 1

the best way to do that is like this

 local autoreply={
['hey']='hi',
['how are u']='am fine what about u?',
['how r u']='am fine what about u?',
['how are you']='am fine what about u?',
['sleep']='rockabye bayby good dreems',
['السلام']='وعليكم السلام ورحمة الله وبركاته',
}
local keys={'hey','how are u','how r u','how are you','sleep','السلام'}
function getValueFromKey(table,key)
  for k,v in ipairs(keys)do
  if string.find(string.upper(key),string.upper(v)) then return table[v] end
  end
   return false
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" )

Answer 3

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