序列检测

Question

我有一组来自传感器的事件。该集看起来类似于：

@[{@"type":@1,@"date":"2014-01-01 17:00"},
{@"type":@3,@"date":"2014-01-01 17:01"  },
{@"type":@1,@"date":"2014-01-01 17:02"  },
{@"type":@1,@"date":"2014-01-01 17:02"  },
{@"type":@1, @"date":"2014-01-01 17:03" },
{@"type":@2,@"date":"2014-01-02 17:04"  },
{@"type":@2,@"date":"2014-01-02 17:04"  },  
{@"type":@2,@"date":"2014-01-02 17:04"  }
]; 

因此，有一种类型的事件与其他类型的单一事件混合在一起。我想检测事件的顺序。如果我只查看事件的类型我有一个数组@ [1,3,1,1,2,2,1,2] 我可以清楚地看到3和1不属于那里，事件的顺序应该是： @ [1,2]看起来最简单的方法就是删除那些不匹配的事件。

-(NSInteger)locationCheckForProximityEvents:(NSArray *)proximityEvents andDate:(NSDate *)date{

    NSInteger accuracy = 7; // time in seconds to be evaluated
    NSArray * lastEvents = [proximityEvents filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(NSDictionary * evaluatedObject, NSDictionary *bindings) {
        NSDate * edate = [evaluatedObject objectForKey:@"date"];            
        NSInteger proximity =[[evaluatedObject objectForKey:@"proximity"] integerValue];
        NSInteger diff = [date timeIntervalSinceDate:edate];

        if(diff<accuracy&&(proximity!=CLProximityUnknown)){
            return  YES;
        }
        return NO;
    }]];

    //we are returning -1
    if(lastEvents.count == 0) return -1;

    NSInteger first= lastEvents.count <accuracy ? 0:lastEvents.count-accuracy;
    NSInteger count =lastEvents.count > accuracy? accuracy:lastEvents.count;
    NSArray * lastTen = [lastEvents subarrayWithRange: NSMakeRange(first
                                                                   , count)  ];

    NSArray * beds = [lastTen filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(type==%@)",@(kbed)]]; 
    NSArray * sinks = [lastTen filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(type==%@)",@(ksink)]];
    NSArray * briefings = [lastTen filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(type==%@)",@(kbriefing)]];
    NSArray * simlabs = [lastTen filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(type==%@)",@(kroom)]];

    if(beds.count >0 && beds.count>= (count -1)/2){
        return kbed;
    }

    if(briefings.count > 0 && briefings.count > count/2){
        return kbriefing;
    }

    if(simlabs.count>0 && simlabs.count > count/2){
        return kroom;
    }


    return -1;
}