Door detector

local sens = peripheral.wrap("left")
local outside = "top"
local door = false
local radius = 5

door = false
redstone.setOutput(outside, (not door))

function getPos(username)
    local ok, player = pcall(sens.getPlayerByName, username)
    if ok then
        return player.select("living").position
    end
end

function chkDoor()
  redstone.setOutput(outside, (not door))
end

function chkPlayer()
    local players = sens.getPlayers()

    if #players ~= 0 then
        for k=1,#players do

            local pos = getPos(players[k].name)
            if pos and pos.x >= (radius * -1) and pos.x <= radius
                and pos.y >= (radius * -1) and pos.y <= radius
                and pos.z >= (radius * -1) and pos.z <= radius then
    --          print(username.."is in the spot. Opening Door.")
                door = true
                return
            end
        end
    end

    door = false
end

while true do
    sleep(0.5)
    chkDoor()
    chkPlayer()
end