svn: r154

collects/mztake/demos/random/random-Xs-test-v2.ss

@@ -0,0 +1,115 @@
+#|   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 trends in the numbers.
+
+     Look for tortoises that stay low and black, and hares which are very
+     active and bright.
+
+     Notice how the bottom tends to be rather patchy with lots of color
+     variation (the "start-up" phase of the random number generator),
+     and then towards the middle of the screen, most of the blues have
+     settled down and evened out.
+
+     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 and horizontal trends more easily.  |#
+
+
+(require (lib "graphics.ss" "graphics")
+         #| Needed for open-graphics, open-viewport, and draw-solid-ellipse |#
+         
+         (lifted mzscheme
+                 hash-table-for-each
+                 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 |#
+
+(define total-count (count-b x-trace))
+
+(printf-b "count: ~a" total-count)
+#| prints the count of how many events x-trace got,
+   aka how many values are in the histogram and on the screen. |#
+
+
+(hold (x-trace . -=> .(printf-b "highest bin 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)))])
+           
+           (when (zero? (modulo (value-now total-count) 1000))
+             (hash-table-for-each
+              valcount
+              (lambda (x v)
+                (let ([color (min 1 (* 50 (/ v 1000)))])
+                  ((draw-solid-rectangle window) (make-posn (* x 6)
+                                                            (- 500 (* 10 (/ (value-now total-count) 1000))))
+                                                 6 10 ;; width height
+                                                 (make-rgb 0 (* 0.75 color) color)))))
+             (set! valcount (make-hash-table))
+             (set! largest-bin 0))
+           
+           (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.
+       
+       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. |#
+
+
+(start/resume p) ;; Start the process for random-xs.ss