Data commit

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

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+#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;
+}