Question

I have 2 functions in Lua which create a dictionary table and allow to check if a word exists:

local dictTable = {}
local dictTableSize = 0

function buildDictionary()
    local path = system.pathForFile("wordlist.txt")
    local file = io.open( path, "r")
    if file then
        for line in file:lines() do
            dictTable[line] = true
            dictTableSize = dictTableSize + 1
        end      
        io.close(file)
    end
end

function checkWord(word)
    if dictTable[word] then
        return(true)
    else
        return(false)
    end
end

Now I want to be able to generate a couple of random words. But since the words are the keys, how can I pick some, given the dictTableSize.

Thanks

Answer 1

Just add a numerical index for each word to the dictionary while loading it:

function buildDictionary()
    local path = system.pathForFile("wordlist.txt")
    local file = io.open( path, "r")
    if file then
        local index = 1
        for line in file:lines() do
            dictTable[line] = true
            dictTable[index] = line
            index = index + 1
        end      
        io.close(file)
    end
end

Now you can get a random word like this:

function randomWord()
    return dictTable[math.random(1,#dictTable)]
end

---

Side note: nil evaluates to false in Lua conditionals, so you could write checkWord like this:

function checkWord(word)
    return dictTable[word]
end

---

Another side note, you’ll get less polution of the global namespace if you wrap the dictionary functionality into an object:

local dictionary = { words = {} }

function dictionary:load()
    local path = system.pathForFile('wordlist.txt')
    local file = io.open( path, 'r')
    if file then
        local index = 1
        for line in file:lines() do
            self.words[line] = true
            self.words[index] = line
            index = index + 1
        end      
        io.close(file)
    end
end

function dictionary:checkWord(word)
    return self.words[word]
end

function dictionary:randomWord()
    return self.words[math.random(1,#self.words)]
end

Then you can say:

dictionary:load()
dictionary:checkWord('foobar')
dictionary:randomWord()