-- the location of the redstone lamp relative to the sensor
local offset = {
  X = 1,
  Y = 1,
  Z = 0
}

-- how close a player has to be to activate the lamp
local radius = 5

 -- find the distance from the player position to the offset
function distance(pos)
  local xd = pos.X - offset.X
  local yd = pos.Y - offset.Y
  local zd = pos.Z - offset.Z
  return math.sqrt(xd*xd + yd*yd + zd*zd)
end


local proximity = peripheral.wrap("left")
while true do
  local signal = false
  local targets = proximity.getPlayers()
  for k, v in pairs(targets) do
        if distance(v.Position) < radius then
          signal = true
        end
  end
  rs.setOutput("top", signal)
end