147 lines
3.2 KiB
Lua
147 lines
3.2 KiB
Lua
--[[
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data.lua: property and methods for manipulating incoming measurements
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Copyright (c) 2009 jokamajo.org
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2010 - 2011 Bart Van Der Meerssche <bart.vandermeerssche@flukso.net>
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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]]--
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local os, math, table, string =
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os, math, table, string
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local getfenv, setmetatable, pairs, ipairs =
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getfenv, setmetatable, pairs, ipairs
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module (...)
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local modenv = getfenv() -- module environment
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-- private
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local function timestamps(T)
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local H = {} -- helper table, an indexed array containing all the measurement's timestamps
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for timestamp in pairs(T) do
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H[#H+1] = timestamp
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end
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table.sort(H) -- sort in ascending order, oldest timestamps will be treated first
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return H
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end
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function new()
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return setmetatable({}, {__index = modenv})
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end
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function add(M, sensor, timestamp, value)
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if not M[sensor] then
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M[sensor] = {}
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end
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M[sensor][timestamp] = value
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end
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function get_sensors(M)
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local S = {}
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for sensor in pairs(M) do
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S[#S+1] = sensor
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end
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return S
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end
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function clear(M, sensor)
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if sensor then
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M[sensor] = nil
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else -- clear all
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for sensor in pairs(M) do
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M[sensor] = nil
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end
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end
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end
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function filter(M, span, offset)
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for sensor, T in pairs(M) do
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local H = timestamps(T)
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local i = 2
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while not (H[i+1] == nil or H[i] > os.time()-offset) do
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if math.floor(H[i-1]/span) == math.floor(H[i]/span) and
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math.floor(H[i]/span) == math.floor(H[i+1]/span) then
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T[H[i]] = nil
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table.remove(H, i)
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else
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i = i+1
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end
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end
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end
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end
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function polish(M, now, cutoff)
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for sensor, T in pairs(M) do
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local H = timestamps(T)
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-- fill up the holes first
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for i = H[#H]-1, H[1]+1, -1 do
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if T[i] == nil or T[i] == '"nan"' then
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T[i] = T[i+1]
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end
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end
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-- make sure the tail stretches up to 'now'
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for i = H[#H]+1, now do
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T[i] = '"nan"'
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end
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-- truncate the head
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for i = H[1], now - cutoff do
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T[i] = nil
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end
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end
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end
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function json_encode(M, entries)
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local J = {}
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if entries then
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arr_size = 5*entries + 2
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else
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arr_size = 0
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end
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for sensor, T in pairs(M) do
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local H = timestamps(T)
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local SB = table.create(arr_size, 0)
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SB[1] = '[' -- use a string buffer for building up the JSON string
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for k, timestamp in ipairs(H) do
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SB[#SB+1] = '['
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SB[#SB+1] = timestamp
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SB[#SB+1] = ','
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SB[#SB+1] = T[timestamp]
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SB[#SB+1] = '],'
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end
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SB[#SB] = SB[#SB]:sub(1, -2) -- remove the trailing comma from the last entry
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SB[#SB+1] = ']'
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J[sensor] = table.concat(SB)
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end
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return J
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end
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