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LURE: spy

Watch over a stream, regularly reporting

tim@menzies.us
August'17 

require "show"
local the=require "config"
local NUM=require "num"

Create a new watcher

 
local function create(n)  return {
  reportEvery = n,
  m           = 0,
  stats       = NUM.create(),
  all         = {}
} end

Report

 
local function report(i,x) 
  print{n=i.stats.n, mu=i.stats.mu, sd=i.stats.sd} end

Update watcher i with one value x

 
local function update(i,x) 
  if x~= the.ignore then
    i.m = i.m + 1
    NUM.update(i.stats,x)
    if i.m % i.reportEvery == 0 then
      i.all[#i.all + 1] = i.stats
      report(i)
      i.stats = NUM.create() end end
  return i end

Handy short cut

 
local function watch(n)
  local i=create(n)
  return i, function (x) return update(i,x) end end

Update a watcher i with many values from t. Optionally:

  • filter every value in t through some function f.
  • If an filter every value in t through some function f.
  • If an all value is supplied, the update all. Else return a new watcher.
 
local function updates(lst,f,i)
  i = i or create()
  f = f or function (z) return z end
  for _,one in pairs(lst) do
    update(i, f(one)) end 
  return i end

Public interface

 
return {create=create, update=update, updates=updates, 
        watch=watch, report=report}

Legal

LURE, Copyright (c) 2017, Tim Menzies All rights reserved, BSD 3-Clause License

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  • Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.