Question

I am trying to get the compare an object in an NSArray with two objects in two different NSArrays and i want to store the first occurence of the object and discard the next.

e.g:-

I have an Array1 where it contains objects like (20.12, 20.15, 21.4, 22.6, 23.0, 24.2, 28.7, 30.5, 30.9, 32.6, 33.7).
Now i have another Array2 that contains objects like (20.00, 22.0, 28.0, 30.0, 33.0) and another Array3 that contains objects like (21.0, 24.0, 29.0, 32.0, 34.0)

Now i want to store the first objects that are in between (20.00 – 21.0, 22.0 – 24.0, 28.0 – 29.0, 30.0 – 32.0, 33.0 – 34.0). I have tried to implement this by using

if (clickTimeInterval >= [[Array2 objectAtIndex:i] doubleValue] && clickTimeInterval <= [[Array3 objectAtIndex:i] doubleValue]) {

My clickTimeInterval is the time interval stored in my Array1. I am able to get the values but i just want to store the values that comes first and store into Array4. It looks something like Array4 = (20.12, 22.6, 24.2, 28.7, 30.5, 33.7). Can anyone please help me out on how to get this?

Answer 1

It depends on how optimized you want to be. Here’s a version that re-samples “Array1” for each range. If you have a large number of objects to filter (and they are sorted), you could store the last found location to make subsequent searches quicker.

- (NSArray *)bucketTest {
    NSMutableArray *result = [NSMutableArray array];

    NSArray *samples = [NSArray arrayWithObjects:[NSNumber numberWithDouble:1.1], [NSNumber numberWithDouble:1.5], [NSNumber numberWithDouble:2.2], nil];
    NSArray *lows = [NSArray arrayWithObjects:[NSNumber numberWithDouble:1.0], [NSNumber numberWithDouble:2.0], nil];
    NSArray *highs = [NSArray arrayWithObjects:[NSNumber numberWithDouble:2.0], [NSNumber numberWithDouble:3.0], nil];
    for (int bucket = 0; bucket < [lows count]; bucket++) {
        double low = [[lows objectAtIndex:bucket] doubleValue];
        double high = [[highs objectAtIndex:bucket] doubleValue];
        for (NSNumber *sample in samples) {
            if (([sample doubleValue] >= low) && ([sample doubleValue] < high)) {
                [result addObject:sample];
                break;
            }
        }
    }
    return result;
}