CODEWITHSUNDEEP
iosobjective-carrayssorting
Julian
Julian

Reputation: 9

Grouping NSArray By Looping?

I am trying to isolate elements in an array. I have an NSArray containing over 100000 NSNumber Objects. The problem I have is they are arranged by increments of 3. 

processarray = [[NSMutableArray alloc] init];

for (loopstart = 0; loopstart < arraycount; loopstart ++)

{
    arrayvalue = [[mesharray objectAtIndex: loopstart] floatValue];
    coordinate = [NSNumber numberWithFloat: arrayvalue];
    [processarray addObject: coordinate];
    [printgcodetoconsole appendFormat: @"\nCOORDINATE: %@", coordinate];

}

For Example, my array looks like this:

What I need is a way to group the correct values together in terms of X, Y, and Z because they are points in space like:

and so on…

There are no similarities between the objects in the array except that they are all NSNumber objects.

Thanks In Advance!

I am currently printing this array as strings in a NSTextView and I can't figure out how to isolate the strings without messing up the loop with this code:

[printgcodetoconsole appendFormat: @"\nCOORDINATE: %@", coordinate];

I would really prefer something more like:

NSNumber * X;
NSNumber * Y;
NSNumber * Z;

[printgcodetoconsole appendFormat: @"\n X%@, Y%@, Z%@", X, Y, Z];

Upvotes: 0

Views: 221

Answers (3)

Julian
Julian

Reputation: 9

Thanks a lot guys… the answer turned out to be a variation on JeroValli's idea about using a modulo. It's a damn sexy idea I might add. Thanks Jero and everyone else involved.

for (loopstart = 0; loopstart < arraycount; loopstart ++)

        {
            arrayvalue = [[mesharray objectAtIndex: loopstart] floatValue];
            point = [NSNumber numberWithFloat: arrayvalue];
            [coordinates addObject: point];
            if (loopstart % 3 == 0)
            {
                [printgcodetoconsole appendFormat: @"\nCOORDINATE: X%@", point];
            }
            else if (loopstart % 3 == 1)
            {
                [printgcodetoconsole appendFormat: @"\nCOORDINATE: Y%@", point];
            }
            else if (loopstart % 3 == 2)
            {
                [printgcodetoconsole appendFormat: @"\nCOORDINATE: Z%@", point];
            }

Upvotes: 0

dreamlax
dreamlax

Reputation: 95335

This simple code will take every three items from meshArray, put them into a new array and insert that into a larger array (so that you have an array of arrays).

NSArray *meshArray = /* obtain from somewhere */;
NSAssert(([meshArray count] % 3) == 0, @"Array does not contain multiple of 3");

NSMutableArray coordinates = [NSMutableArray array];

for (NSUInteger i = 0; i < [meshArray count]; i += 3)
    [coordinates addObject:[meshArray subarrayWithRange:NSMakeRange(i, 3)]];

Alternatively, if you want, you can key them using a dictionary:

NSArray *meshArray = /* obtain from somewhere */;
NSAssert(([meshArray count] % 3) == 0, @"Array does not contain multiple of 3");

NSMutableArray coordinates = [NSMutableArray array];

for (NSUInteger i = 0; i < [meshArray count]; i += 3)
{
    NSDictionary *coordinate = @{ @"X" : meshArray[i], @"Y" : meshArray[i + 1], @"Z" : meshArray[i + 2] };
    [coordinates addObject:coordinate];
}

Upvotes: 0

JeroValli
JeroValli

Reputation: 569

You should check when the counter loopstart is multiple of 3 and group the last 3 values on a sub-array:

NSMutableArray *subArray = [NSMutableArray array];
for (loopstart = 0; loopstart < arraycount; loopstart ++) {
    arrayvalue = [[mesharray objectAtIndex:loopstart] floatValue];
    coordinate = [NSNumber numberWithFloat: arrayvalue];
    [subArray addObject:coordinate];
    if (loopstart % 3 == 0) {
        [processarray addObject:subArray];
        subArray = [NSMutableArray array];
    }
}

Upvotes: 1

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