From 2f46304b4eb4ccb0ddb6ca7d5e162253d5644d3e Mon Sep 17 00:00:00 2001
From: Jono Spiro <jono.spiro@gmail.com>
Date: Sun, 8 Aug 2004 00:17:26 +0000
Subject: [PATCH] fixed

svn: r162
---
 .../mztake/demos/random/random-xs-test.ss     | 107 ++++++++++++++++++
 collects/mztake/demos/random/random-xs.ss     |   5 +
 2 files changed, 112 insertions(+)
 create mode 100644 collects/mztake/demos/random/random-xs-test.ss
 create mode 100644 collects/mztake/demos/random/random-xs.ss

diff --git a/collects/mztake/demos/random/random-xs-test.ss b/collects/mztake/demos/random/random-xs-test.ss
new file mode 100644
index 0000000000..a36d725f97
--- /dev/null
+++ b/collects/mztake/demos/random/random-xs-test.ss
@@ -0,0 +1,107 @@
+#|   The program being debugged (a module in the file "random-xs.ss") runs an infinite loop,
+     binding "x" to a random number between [0,100) each iteration.
+     
+     This MzTake script draws a histogram of the values of x seen over time,
+     in sync with the execution of "random-xs.ss". This will run until one
+     bar reaches the top of the screen.     
+
+     This histogram provides three pieces of information:
+      * Each bar represents a bin, the height represents how many times
+        that "random" number was generated.
+
+      * The brighter the blue, the faster that bin is growing compared
+        to the others. The darker, the slower.
+
+      * You can see a history of speeds over time based on how the colors
+        change in each bin.
+
+     Try looking for small groupings of bins where all are light, or all
+     are dark -- these represent small trends in the numbers.
+
+     Look for tortoises that stay low and black, and hares which are very
+     active and bright.
+
+     The bars drag a bit when moving upwards (the height goes up by 2, but
+     the redrawing of the latest color goes down 10 pixels) so that you can
+     spot vertical trends more easily.  |#
+
+
+(require (lib "graphics.ss" "graphics")
+         #| Needed for open-graphics, open-viewport, and draw-solid-ellipse |#
+         
+         (lifted mzscheme
+                 make-hash-table
+                 hash-table-put!
+                 hash-table-get))
+#|       "Lifted" is explained in FrTime's own documentation (plt/collects/frtime/doc.txt)
+          Quickly put, lifting extends the functions listed above so they can take FrTime time-varying
+          values (such as MzTake traces) as arguments. |#
+
+
+
+(open-graphics)
+(define window (open-viewport "Debugger" 600 500))
+((draw-viewport window) (make-rgb 0.95 0.95 0.95))
+#| This file doesn't animate a list of objects since the number of
+   objects quickly reaches the thousands (slowing drawing time severly),
+   and they are stationary -- so we just keep drawing the circles at
+   their new heights based on the value in the hashtable.
+
+   See the doc for more information on this kind of drawing. |#
+
+
+
+(define-mztake-process p ("random-xs.ss" [x-trace 4 6 bind 'x]))
+#| * Create a process to debug random-xs.ss
+
+   * Add a tracepoint at line 4, column 6; in the program,
+     this is right before the next iteration of the loop is called,
+     ->(loop (random 200))
+
+   * At this tracepoint, define "x-trace" to a FrTime eventstream that
+     recieves events containing the latest value of "x" seen,
+     every time the code at line 4, column 6, is reached. |#
+
+(define largest-bin 0)
+(define valcount (make-hash-table))
+#| this will hold the counts for the histogram
+   x is the key, and the number of times x shows up is the value |#
+
+
+(hold (x-trace . -=> .(printf-b "largest count: ~a" largest-bin)))
+#| Prints out the largest count every time we get a new x-trace event |#
+
+
+(map-e (lambda (x)
+         (let* ([new-cnt (add1 (hash-table-get valcount x (lambda () 0)))]
+                [color (/ new-cnt (add1 largest-bin))])
+           
+           (when (= largest-bin 250)
+             (kill p))
+           ; when one of the bars reaches the top of the screen, kill the program.
+           
+           (when (> new-cnt largest-bin) (set! largest-bin new-cnt))
+           ; keep track of the largest count
+           
+           (hash-table-put! valcount x new-cnt)
+           ;; increment the value in the hashtable, starting from 0 if none exists.
+           
+           ((draw-solid-rectangle window) (make-posn (* x 6)  (- 500 (* 2 new-cnt)))
+                                          6 10 ;; width height
+                                          (make-rgb 0 (* 0.75 color) color))))
+       x-trace)
+#| Every time x-trace gets a new value, take this latest value and pass it to a function
+   which increments the count in the hashtable, and draws a circle in the window at
+   (* x 6) pixels from the left, and the height is (2 * the latest count in the hashtable for that x),
+   making a color (MAKE-RGB) that is lighter based on how fast it is growing.
+|#
+
+
+(printf-b "count: ~a" (count-b x-trace))
+#| prints the count of how many events x-trace got,
+   aka how many values are in the histogram and on the screen.
+|#
+
+
+(start/resume p)
+;; Start the process for random-xs.ss
\ No newline at end of file
diff --git a/collects/mztake/demos/random/random-xs.ss b/collects/mztake/demos/random/random-xs.ss
new file mode 100644
index 0000000000..111122d58f
--- /dev/null
+++ b/collects/mztake/demos/random/random-xs.ss
@@ -0,0 +1,5 @@
+(module random-xs mzscheme
+  (define (run)
+    (let loop ([x (random 100)])
+      (loop (random 100))))
+  (run))
\ No newline at end of file