March 2014 update

Task/Averages-Simple-moving-average/Brat/averages-simple-moving-average-1.brat

@@ -0,0 +1,21 @@
+SMA = object.new
+
+SMA.init = { period |
+  my.period = period
+  my.list = []
+  my.average = 0
+}
+
+SMA.prototype.add = { num |
+  true? my.list.length >= my.period
+    { my.list.deq }
+
+  my.list << num
+  my.average = my.list.reduce(:+) / my.list.length
+}
+
+sma3 = SMA.new 3
+sma5 = SMA.new 5
+[1, 2, 3, 4, 5, 5, 4, 3, 2, 1].each { n |
+  p n, " - SMA3: ", sma3.add(n), " SMA5: ", sma5.add(n)
+}

Task/Averages-Simple-moving-average/Brat/averages-simple-moving-average-2.brat

@@ -0,0 +1,17 @@
+sma = { period |
+  list = []
+
+  { num |
+    true? list.length >= period
+      { list.deq }
+
+    list << num
+    list.reduce(:+) / list.length
+  }
+}
+
+sma3 = sma 3
+sma5 = sma 5
+[1, 2, 3, 4, 5, 5, 4, 3, 2, 1].each { n |
+  p n, " - SMA3: ", sma3(n), " SMA5: ", sma5(n)
+}

Task/Averages-Simple-moving-average/D/averages-simple-moving-average-1.d

@@ -1,25 +1,24 @@
 import std.stdio, std.traits, std.algorithm;
 
 auto sma(T, int period)() {
-    T[period] data = 0; // D FP are default-initialized to NaN
+    T[period] data = 0;
     T sum = 0;
-    int index, nfilled;
+    int index, nFilled;
 
-    // return (in T v) nothrow {
-    return delegate (in T v) nothrow {
+    return (in T v) nothrow {
         sum += -data[index] + v;
         data[index] = v;
         index = (index + 1) % period;
-        nfilled = min(period, nfilled + 1);
-        return cast(CommonType!(T, float))sum / nfilled;
+        nFilled = min(period, nFilled + 1);
+        return CommonType!(T, float)(sum) / nFilled;
     };
 }
 
 void main() {
-    auto s3 = sma!(int, 3)();
-    auto s5 = sma!(double, 5)();
+    immutable s3 = sma!(int, 3);
+    immutable s5 = sma!(double, 5);
 
-    foreach (e; [1, 2, 3, 4, 5, 5, 4, 3, 2, 1])
+    foreach (immutable e; [1, 2, 3, 4, 5, 5, 4, 3, 2, 1])
         writefln("Added %d, sma(3) = %f, sma(5) = %f",
                  e, s3(e), s5(e));
 }

Task/Averages-Simple-moving-average/D/averages-simple-moving-average-2.d

@@ -3,14 +3,14 @@ import std.stdio, std.traits, std.algorithm;
 struct SMA(T, int period) {
     T[period] data = 0;
     T sum = 0;
-    int index, nfilled;
+    int index, nFilled;
 
     auto opCall(in T v) pure nothrow {
         sum += -data[index] + v;
         data[index] = v;
         index = (index + 1) % period;
-        nfilled = min(period, nfilled + 1);
-        return cast(CommonType!(T, float))sum / nfilled;
+        nFilled = min(period, nFilled + 1);
+        return CommonType!(T, float)(sum) / nFilled;
     }
 }
 
@@ -18,7 +18,7 @@ void main() {
     SMA!(int, 3) s3;
     SMA!(double, 5) s5;
 
-    foreach (e; [1, 2, 3, 4, 5, 5, 4, 3, 2, 1])
+    foreach (immutable e; [1, 2, 3, 4, 5, 5, 4, 3, 2, 1])
         writefln("Added %d, sma(3) = %f, sma(5) = %f",
                  e, s3(e), s5(e));
 }

Task/Averages-Simple-moving-average/Objective-C/averages-simple-moving-average.m

@@ -0,0 +1,94 @@
+#import <Foundation/Foundation.h>
+
+@interface MovingAverage : NSObject {
+	unsigned int period;
+	NSMutableArray *window;
+	double sum;
+}
+- (instancetype)initWithPeriod:(unsigned int)thePeriod;
+@end
+
+@implementation MovingAverage
+
+// init with default period
+- (instancetype)init {
+	self = [super init];
+	if(self) {
+		period = 10;
+		window = [[NSMutableArray alloc] init];
+		sum = 0.0;
+	}
+	return self;
+}
+
+// init with specified period
+- (instancetype)initWithPeriod:(unsigned int)thePeriod {
+	self = [super init];
+	if(self) {
+		period = thePeriod;
+		window = [[NSMutableArray alloc] init];
+		sum = 0.0;
+	}
+	return self;
+}
+
+// add a new number to the window
+- (void)add:(double)val {
+	sum += val;
+	[window addObject:@(val)];
+	if([window count] > period) {
+		NSNumber *n = window[0];
+		sum -= [n doubleValue];
+		[window removeObjectAtIndex:0];
+	}
+}
+
+// get the average value
+- (double)avg {
+	if([window count] == 0) {
+		return 0; // technically the average is undefined
+	}
+	return sum / [window count];
+}
+
+// set the period, resizes current window
+- (void)setPeriod:(unsigned int)thePeriod {
+	// make smaller?
+	if(thePeriod < [window count]) {
+		for(int i = 0; i < thePeriod; ++i) {
+			NSNumber *n = window[0];
+			sum -= [n doubleValue];
+			[window removeObjectAtIndex:0];
+		}
+	}
+	period = thePeriod;
+}
+
+// get the period (window size)
+- (unsigned int)period {
+	return period;
+}
+
+// clear the window and current sum
+- (void)clear {
+	[window removeAllObjects];
+	sum = 0;
+}
+
+@end
+
+int main (int argc, const char * argv[]) {
+	@autoreleasepool {
+		double testData[10] = {1,2,3,4,5,5,4,3,2,1};
+		int periods[2] = {3,5};
+		for(int i = 0; i < 2; ++i) {
+			MovingAverage *ma = [[MovingAverage alloc] initWithPeriod:periods[i]];
+			for(int j = 0; j < 10; ++j) {
+				[ma add:testData[j]];
+				NSLog(@"Next number = %f, SMA = %f", testData[j], [ma avg]);
+			}
+			NSLog(@"\n");
+		}
+	}
+	return 0;
+}

Task/Averages-Simple-moving-average/Perl-6/averages-simple-moving-average.pl6

@@ -1,8 +1,7 @@
-sub sma(Int $period where * > 0) returns Sub {
+sub sma(Int \P where * > 0) returns Sub {
     sub ($x) {
-        state @a = 0 xx $period;
-        @a.push($x);
-        @a.shift;
-        $period R/ [+] @a;
+        state @a = 0 xx P;
+        @a.push($x).shift;
+        P R/ [+] @a;
     }
 }

Task/Averages-Simple-moving-average/Perl/averages-simple-moving-average.pl

@@ -1,7 +1,18 @@
-sub sma ($)
- {my ($period, $sum, @a) = shift, 0;
-  return sub
-     {unshift @a, shift;
-      $sum += $a[0];
-      @a > $period and $sum -= pop @a;
-      return $sum / @a;}}
+sub sma_generator {
+    my $period = shift;
+    my (@list, $sum);
+
+    return sub {
+        my $number = shift;
+        push @list, $number;
+        $sum += $number;
+        $sum -= shift @list if @list > $period;
+        return $sum / @list;
+    }
+}
+
+# Usage:
+my $sma = sma_generator(3);
+for (1, 2, 3, 2, 7) {
+    printf "append $_ --> sma = %.2f  (with period 3)\n", $sma->($_);
+}