* guile: some internal improvements

guile/mu/stats.scm

@@ -21,17 +21,22 @@
   :use-module (mu message)
   :use-module (srfi srfi-1)
   :use-module (ice-9 i18n)
-  :export ( mu:tabulate-messages
-	    mu:average-messages
+  :use-module (ice-9 r5rs)
+  :export ( mu:tabulate
+	    mu:average
+	    mu:stddev
 	    mu:weekday-numbers->names
 	    mu:month-numbers->names))
 
-(define* (mu:tabulate-messages func #:optional (expr #t))
+
+(define* (mu:tabulate func #:optional (expr #t))
   "Execute FUNC for each message matching EXPR, and return an alist
 with maps each result of FUNC to its frequency. FUNC is a function
 takes a <mu-message> instance as its argument. For example, to
 tabulate messages by weekday, one could use:
-   (mu:tabulate-messages (lambda(msg) (tm:wday (localtime (date msg)))))."
+   (mu:tabulate (lambda(msg) (tm:wday (localtime (date msg))))), and
+get back a list like
+   ((1 . 2) (2 . 5)(3 . 4)(4 . 4)(5 . 12)(6 . 7)(7. 2))."
   (let ((table '()))
     (mu:for-each-message
       (lambda(msg)
@@ -41,34 +46,52 @@ tabulate messages by weekday, one could use:
       expr)
     table))
 
+(define (average lst)
+  "Calculate the average of a list LST of numbers, or #f if undefined."
+  (if (null? lst)
+    #f
+    (/ (apply + lst) (length lst))))
+
+(define (stddev lst)
+  "Calculate the standard deviation of a list LST of numbers or #f if
+undefined."
+  (let* ((avg (average lst))
+	  (sosq (if avg
+		  (apply + (map (lambda (x)(* (- x avg) (- x avg))) lst)))))
+    (if sosq
+      (sqrt (/ sosq (length lst))))))
+
+
+(define* (mu:average func #:optional (expr #t))
+  "Get the average value of FUNC applied to all messages matching
+EXPR (or #t for all). Returns #f if undefined."
+  (average (map func (mu:message-list expr))))
+
+(define* (mu:stddev func #:optional (expr #t))
+  "Get the standard deviation for the the values of FUNC applied to
+all messages matching EXPR (or #t for all). Returns #f if undefined."
+  (stddev (map func (mu:message-list expr))))
+
+
+(define* (mu:max func #:optional (expr #t))
+  "Get the maximum value of FUNC applied to all messages matching
+EXPR (or #t for all). Returns #f if undefined."
+  (apply max (map func (mu:message-list expr))))
+
+(define* (mu:min func #:optional (expr #t))
+  "Get the minimum value of FUNC applied to all messages matching
+EXPR (or #t for all). Returns #f if undefined."
+  (apply min (map func (mu:message-list expr))))
 
-(define* (mu:average-messages func #:optional (expr #t))
-  "Execute FUNC for each message matching EXPR, and return the average
-value of the results of FUNC.  FUNC is a function that takes a
-<mu-message> instance as its argument, and returns some number. For
-example, to get the average message size of messages related to
-icecream:  (mu:average (lambda(msg) (size msg)) \"icecream\" ."
-(let ((count 0) (sum 0))
-  (mu:for-each-message
-    (lambda (msg)
-      (set! count (+1 count))
-      (set! sum (+ sum (func msg))))
-    expr)
-  (if (= count 0)
-    0
-    (exact->inexact (/ sum count)))))
 
 ;; a list of abbreviated, localized day names
 (define day-names
-  (map
-    (lambda (num)
-      (locale-day-short num))
-      (iota 7 1)))
+  (map locale-day-short (iota 7 1)))
 
 (define (mu:weekday-numbers->names table)
   "Convert a list of pairs with the car denoting a day number (0-6)
 into a list of pairs with the car replaced by the corresponding day
-name (abbreviated)."
+name (abbreviated) for the current locale."
     (map
       (lambda (pair)
 	(cons (list-ref day-names (car pair)) (cdr pair)))
@@ -76,10 +99,7 @@ name (abbreviated)."
 
 ;; a list of abbreviated, localized month names
 (define month-names
-  (map
-    (lambda (num)
-      (locale-month-short num))
-      (iota 12 1)))
+  (map locale-month-short (iota 12 1)))
 
 (define (mu:month-numbers->names table)
     "Convert a list of pairs with the car denoting a month number (0-11)