Misc Lua Scripts for Redis

location2d.lua

local radius, x, y = unpack(ARGV)
local locations = redis.call('HGETALL', KEYS[1])
local nearby = {}

for i = 1, #locations, 2 do
  local cid, cloc = locations[i], locations[i+1]
	local cx, cy = string.sub(cloc, 1, 2), string.sub(cloc, 3, 4)

	if (cx - x)^2 + (cy - y)^2  <= radius^2 then
		table.insert(nearby, cid)
	end
end

return nearby

location3d.lua

local radius, x, y, z = unpack(ARGV)
local locations = redis.call('HGETALL', KEYS[1])
local nearby = {}

for i = 1, #locations, 2 do
  local cid, cloc = locations[i], locations[i+1]
	local cx, cy, cz = string.sub(cloc, 1, 2), string.sub(cloc, 3, 4), string.sub(cloc, 5, 6)

	if (cx - x)^2 + (cy - y)^2 + (cz - z)^2  <= radius^2 then
		table.insert(nearby, cid)
	end
end

return nearby