objective-c - Objective-C 中的移动平均线

Question

<分区>

Answer 1

我有其中之一:

// MovingAverage.h

@interface MovingAverage : NSObject

@property (readonly, nonatomic) float movingAverage;
@property (readonly, nonatomic) float cumulativeAverage;

- (id)initWithPeriod:(NSUInteger)period;
- (void)addDatum:(NSNumber *)datum;

@end


// MovingAverage.m

#import "MovingAverage.h"

@interface MovingAverage ()
@property (strong, nonatomic) NSMutableArray *queue;
@property (assign, nonatomic) NSUInteger period;
@property (assign, nonatomic) NSUInteger count;
@property (assign, nonatomic) float movingAverage;
@property (assign, nonatomic) float cumulativeAverage;
@end

@implementation MovingAverage

- (id)initWithPeriod:(NSUInteger)period {

    self = [self init];
    if (self) {
        _period = period;
        // with arc
        _queue = [NSMutableArray array];
        // without arc
        _queue = [[NSMutableArray alloc] init];
    }
    return self;
}

- (void)addDatum:(NSNumber *)datum {

    [self.queue insertObject:datum atIndex:0];

    float removed = 0;
    float datumf = [datum floatValue];

    if (self.queue.count > self.period) {
        removed = [[self.queue lastObject] floatValue];
        [self.queue removeLastObject];
    }

    self.movingAverage = self.movingAverage - (removed / self.period) + (datumf / self.period);

    // compute the cumulative average
    self.cumulativeAverage = self.cumulativeAverage + (datumf - self.cumulativeAverage) / ++self.count;
}

// if non-ARC
- (void)dealloc {
    [_queue release];
    [super dealloc];
}

@end