How to select multiple random elements from a LUA table? - lua

Question

I'm trying to figure out how to randomly select multiple entries in a table.
This is what I have currently
local letters = {"w", "x", "y", "z"}
function randomletterselect()
local randomletters = {}
for i,v in pairs(letters) do
table.insert(randomletters,i)
end
local letter = letters[randomletters[math.random(#randomletters)]]
-- set multiple selected letters to the new table?
end
randomletterselect()
this code here works for selecting ONE random element(letter) from the table. essentially, when I run this, I want it to be multiple random letters selected. for example, one time it may select x,y another time it may be x,y,z.
The closest thing I found was honestly just what I had figured out, in this post Randomly select a key from a table in Lua

Answer 1

You can do...
randomletterselect=function()
local chars={}
for i=65,math.random(65,90) do
table.insert(chars,string.char(math.random(65,90)):lower())
end
print(table.concat(chars,','))
return chars
end
randomletterselect()
...for lowercase letters.
And this version returns a table without doubles...
randomletterselect=function()
local chars=setmetatable({},{__name='randomletters'})
for i=65,90 do
table.insert(chars,string.char(i):lower())
end
for i=1,math.random(#chars) do
table.remove(chars,math.random(#chars))
end
print(#chars,table.concat(chars,','))
return chars
end

Answer 2

local tbl = {'a', 'b', 'c', 'd'} -- your characters here
local MIN_NUM, MAX_NUM = 1, 2 ^ #tbl - 1
-- if the length of the table has changed, MAX_NUM gonna change too
math.randomseed(os.time())
local randomNum = math.random(MIN_NUM, MAX_NUM)
local function getRandomElements(num)
local rsl = {}
local cnt = 1
while num > 0 do
local sign = num % 2 -- to binary
-- if the num is 0b1010, sign will be 0101
num = (num - sign)/2
if sign == 1 then
local idx = #rsl + 1
-- use tbl[#tbl + 1] to expand the table (array)
rsl[idx] = tbl[cnt]
end
cnt = cnt + 1
end
return table.concat(rsl)
end
print(getRandomElements(randomNum))
I have another method to solve the problem, try.
MIN_NUM should be 1 cuz when its 0, getRandomElements will return an empty string