How to Find Duplicate Values in Arrays?

Question

I am working on SQLite and I have written a query which returns me two arrays ItemsArray and CustomersIDArray as:

ItemsArray
Element at Index 0 = Off White,
Element at Index 1 = Fan,
Element at Index 2 = Off White,
Element at Index 3 = Delux,
Element at Index 4 = Fan

CustomerIDArray 
Element at Index 0 = 1,
Element at Index 1 = 2,
Element at Index 2 = 2,
Element at Index 3 = 3,
Element at Index 4 = 4

I want result like that Off White = 2 (count) , Fan = 2 (count) and Delux = 1; and the Resultant Array,

Result Array 
Element at Index 0 = Off White,
Element at Index 1 = Fan,
Element at Index 2 = Delux

Actually I want the count of repetition in first array but the value must not same for CustomerArray. Please help me through logic or code.

Try solution provided on this question: (stackoverflow.com/questions/6841072/…) — iNoob
– iNoob, Commented Apr 23, 2012 at 12:39
@INoob Dear I don't know how to use NSCountedSet.. Can you please tell me ? — Amir iDev
– Amir iDev, Commented Apr 23, 2012 at 12:45

AMayes · Accepted Answer · 2012-04-23 19:06:21Z

3

-(NSMutableArray *)getCountAndRemoveMultiples:(NSMutableArray *)array{

    NSMutableArray *newArray = [[NSMutableArray alloc]initWithArray:(NSArray *)array];
    NSMutableArray *countArray = [NSMutableArray new];
    int countInt = 1;
    for (int i = 0; i < newArray.count; ++i) {
        NSString *string = [newArray objectAtIndex:i];
        for (int j = i+1; j < newArray.count; ++j) {
            if ([string isEqualToString:[newArray objectAtIndex:j]]) {
                [newArray removeObjectAtIndex:j];
                countInt++;
            }
        }
        [countArray addObject:[NSNumber numberWithInt:countInt]];
        countInt = 1;
    }
    NSMutableArray *finalArray = [[NSMutableArray alloc] initWithObjects:newArray, countArray, nil];
    NSLog(@"%@", finalArray);
    return finalArray;

}
- (IBAction)getArrayInfo:(id)sender {
    NSMutableArray *myArray = [[NSMutableArray alloc] initWithObjects:@"Off White", @"Fan", @"Off White", @"Deluxe", @"Fan", nil];
    NSMutableArray *godArray = [self getCountAndRemoveMultiples:myArray];
    NSLog(@"Array from this end = %@", godArray);
}

I just set up -getArrayInfo to test it out. Works fine. As you can see, the array you want to display will be at index:0, and the countArray at index:1.

answered Apr 23, 2012 at 19:06

AMayes

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4 Comments

Amir iDev Over a year ago

its really nice work I commit some changes according to me... Thumbs up :)

Amir iDev Over a year ago

I have another problem can you help me?

AMayes Over a year ago

Sure-- post a question, and leave a link to it as a comment here.

Hashim MH Over a year ago

the above answser is logically incorrect. try with this input NSMutableArray *myArray = [[NSMutableArray alloc] initWithObjects:@"Off White", @"Fan", @"Fan", @"Off White", @"Deluxe", @"Fan", @"Fan", nil]; . you can see count of "fan" is 3 but actually it is four. To correct this issue you need to decrement j after an element is removed from array (otherwise the next string in the array is not evaluated). edited the answer

Mick MacCallum · Accepted Answer · 2012-08-18 02:29:13Z

2

Use NSCountedSet like below

NSMutableArray *ary_res = [[NSMutableArray alloc] init];
    NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:@"11",@"13",@"34",@"9",@"13",@"34",@"9",@"2",nil];
    NSCountedSet *set = [[NSCountedSet alloc] initWithArray:array];
    for(id name in set)
    {
        if([set countForObject:name]==2)
            [ary_res addObject:name];
    }
    //
    NSLog(@"%@",ary_res);

edited Aug 18, 2012 at 2:29

Mick MacCallum

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answered Apr 23, 2012 at 12:58

Narayana Rao Routhu

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2 Comments

Amir iDev Over a year ago

I need result in Array if two time then save 2 again that item if three the save 3 if one then 1.

Amir iDev Over a year ago

Yes ... but also want to know how many times it comes in the Array

chewy · Accepted Answer · 2012-04-23 12:40:42Z

0

try this:

NSArray *copy = [ItemsArray copy];

NSInteger index = [copy count] - 1;

for (id object in [copy reverseObjectEnumerator]) {

    if ([ItemsArray indexOfObject:object inRange:NSMakeRange(0, index)] != NSNotFound) {
        [ItemsArray removeObjectAtIndex:index];
    }
    index--;
}

answered Apr 23, 2012 at 12:40

chewy

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2 Comments

Amir iDev Over a year ago

I Change it and its works for me. its update Items Array. But i also want Count of Repeated items.

Javier Giovannini Over a year ago

I suggest not to use the name copy to the array as people can get confused with the message copy you also used in: NSArray *copy = [ItemsArray copy];

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