Lunatic: add 'stat' module for running statistics.

Also, rewrite the mapastats iterator and the LIZTROOP hitscan timing
in terms of that.

git-svn-id: https://svn.eduke32.com/eduke32@2858 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/Makefile

@@ -167,7 +167,8 @@ ifneq (0,$(LUNATIC))
     GAMEOBJS+= $(OBJ)/luaJIT_BC_con_lang.$o \
                $(OBJ)/luaJIT_BC_lunacon.$o \
                $(OBJ)/luaJIT_BC_geom.$o \
-               $(OBJ)/luaJIT_BC_randgen.$o
+               $(OBJ)/luaJIT_BC_randgen.$o \
+               $(OBJ)/luaJIT_BC_stat.$o
 
     # now, take care of having the necessary symbols (sector, wall, etc.) in the
     # executable no matter what the debugging level

polymer/eduke32/source/lunatic/defs.ilua

@@ -547,6 +547,7 @@ local allowed_modules = {
 
     randgen = require("randgen"),
     geom = require("geom"),
+    stat = require("stat"),
 }
 
 local package_loaded = {}

polymer/eduke32/source/lunatic/dynsymlist

@@ -42,6 +42,7 @@ luaJIT_BC_lunacon;
 luaJIT_BC_con_lang;
 luaJIT_BC_geom;
 luaJIT_BC_randgen;
+luaJIT_BC_stat;
 
 rand_jkiss_u32;
 rand_jkiss_dbl;

polymer/eduke32/source/lunatic/foreachmap.lua

@@ -1,4 +1,4 @@
-#!/usr/local/bin/luajit
+#!/usr/bin/env luajit
 
 -- Generic map iterator.
 

polymer/eduke32/source/lunatic/mapastats.lua

@@ -6,6 +6,10 @@ local string = require "string"
 local math = require "math"
 
 local print = print
+local type = type
+
+local stat = require "stat"
+
 
 module(...)
 
@@ -14,37 +18,29 @@ local function printf(fmt, ...)
     print(string.format(fmt, ...))
 end
 
-
-local N = 0
-
 local sumnumsectors = 0
 local sumnumwalls = 0
 
-local sumratio = 0
-local sumsqratio = 0
+local s = stat.new()
 
 function success(map, fn)
     local ns = map.numsectors
     local nw = map.numwalls
 
-    N = N+1
-
-    sumratio = sumratio + nw/ns
-    sumsqratio = sumsqratio + (nw/ns)^2
+    s:add(nw/ns)
 
     sumnumsectors = sumnumsectors+ns
     sumnumwalls = sumnumwalls+nw
 end
 
 function finish()
-    printf("%d maps\n", N)
+    res = s:getstats()
+
+    printf("%d maps\n", res.n)
     printf("total sectors: %d", sumnumsectors)
     printf("total walls: %d", sumnumwalls)
     printf("total walls / total sectors: %.02f", sumnumwalls/sumnumsectors)
     printf("")
     printf("Walls/sector")
-
-    local meanwpers = sumratio/N
-    printf(" mean: %.02f", meanwpers)
-    printf(" stdev: %.02f", math.sqrt(sumsqratio/N - meanwpers^2))
+    print(res)
 end

polymer/eduke32/source/lunatic/stat.lua

@@ -0,0 +1,89 @@
+-- Statistics module for Lunatic.
+
+local ffi = require("ffi")
+
+local math = require("math")
+local string = require("string")
+
+
+module(...)
+
+
+ffi.cdef[[
+typedef struct {
+    double n;
+    double m, s;
+    double min, max;
+} runningstat_t;
+
+typedef struct {
+    const double n;
+    const double mean, var, std;
+    const double min, max;
+} runningstat_res_t;
+]]
+
+
+local res_mt = {
+    __tostring = function(s)
+        return
+            string.format("N=%d; mean=%.5g, std=%.5g; min=%.5g, max=%.5g",
+                         s.n, s.mean, s.std, s.min, s.max)
+    end
+}
+local rstatres = ffi.metatype("runningstat_res_t", res_mt)
+
+
+local mt = {
+    __tostring = function(s)
+        -- XXX: with this and the other serializing of ffi types, take care of
+        -- NaN and Infs when reading back (e.g. by "nan=0/0" in that context)
+        return "stat.new("..s.n..","..s.m..","..s.s..","..s.min..","..s.max..")"
+    end,
+
+    -- See: Accurately computing running variance, by John D. Cook
+    -- http://www.johndcook.com/standard_deviation.html
+    __index = {
+        add = function(s, num)
+            if (s.n > 0) then
+                -- N>0, recurrence
+                s.n = s.n+1
+
+                local lastm = s.m
+                s.m = lastm + (num-lastm)/s.n
+                s.s = s.s + (num-lastm)*(num-s.m)
+
+                if (num < s.min) then s.min = num end
+                if (num > s.max) then s.max = num end
+            else
+                -- N==0, initialization
+                s.n = 1
+
+                s.m = num
+                s.s = 0
+
+                s.min = num
+                s.max = num
+            end
+        end,
+
+        getstats = function(s)
+            local var = s.n > 1 and s.s/(s.n-1) or 0/0
+            return rstatres(s.n, s.m, var, math.sqrt(var), s.min, s.max)
+        end,
+    },
+}
+local rstat = ffi.metatype("runningstat_t", mt)
+
+function new(n,m,s, min,max)
+    if (n == nil) then
+        -- initialization containing no elements
+        return rstat(0, 0, 0/0, 0/0, 0/0)
+    elseif (m == nil) then
+        -- same as initialization with N==0 above (one element)
+        return rstat(1, n, 0, n, n)
+    else
+        -- generic initialization (internal use only)
+        return rstat(n,m,s, min,max)
+    end
+end

polymer/eduke32/source/lunatic/test.elua

@@ -229,6 +229,9 @@ gameevent(gv.EVENT_ENTERLEVEL,
           end
          )
 
+local stat = require("stat")
+local hs = stat.new()
+
 gameactor(1680,  -- LIZTROOP
           function(i, playeri, dist)
               sprite[i].pal = math.random(32)
@@ -239,8 +242,13 @@ gameactor(1680,  -- LIZTROOP
               local x,y,z = spr.x, spr.y, spr.z
               local t = gv.gethitickms()
               local hit = hitscan(x,y,z, spr.sectnum, 10, 10, 0, gv.CLIPMASK0)
-              printf("hitscan took %.03f us, sec=%d, wal=%d, spr=%d", 1000*(gv.gethitickms()-t),
-                    hit.hitsect, hit.hitwall, hit.hitsprite)
+
+              hs:add(1000*(gv.gethitickms()-t))
+
+              if (hs.n == 300) then
+                  printf("hitscan: %s", tostring(hs:getstats()))
+                  hs = stat.new()
+              end
           end
          )