Reduce stacks of duplicates in an array into only one of them in c#

Question

I'll take it directly: For example I have an array

int[] integers = {1, 2, 2, 2, 4, 5, 2, 2, 2};

And all I like is to reduce all the stacks of 2 into only one 2. I need to get this at the end:

{1, 2, 4, 5, 2};

I read about the .Distinct() method and every kind of comparers, but that method deletes all the same elements and I don't want this. I still think there shold be some certain method to do it via Linq or somethig. Thanks!

Check this out http://stackoverflow.com/questions/3350641/array-remove-duplicate-elements — Full Stack Developer - Java, Apr 27 '16 at 15:15
If I understand you, what you want is something that does the same thing as [the Unix ``uniq`` utility](http://linux.die.net/man/1/uniq), except that it acts on the entries of an array rather than on the lines of a file. — David K, Apr 27 '16 at 16:09
What language are you using? There seem to be "unique" functions in many languages, but they eliminate _all_ duplicates, not just consecutive ones. Here is what someone had to do to work around this in Ruby, for example: http://stackoverflow.com/questions/4576652/how-do-you-merge-consecutive-repeating-elements-in-an-array — David K, Apr 27 '16 at 16:16
@David K thanks, I'm gonna check that Ruby out, I think I'm gonna be ok with that. Gonna post a refference as soon as I'm done. — D. Petrov, Apr 28 '16 at 05:49

score 1 · Accepted Answer · answered Apr 28 '16 at 06:33

1

Use the LINQ, Luke!

var result = integers.Where((n, i) =>
    i == 0 ? true : n != integers[i - 1]);

More concise:

var result = integers.Where((n, i) =>
    i == 0 || n != integers[i - 1]);

answered Apr 28 '16 at 06:33

Alexander Petrov

13,457
2
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49

Exactly what I needed. Thanks! – D. Petrov Apr 28 '16 at 15:29

score 0 · Answer 2 · answered Apr 28 '16 at 05:55

I think .net doesn't have function for this.

So you should use simple foreach.

var result = List<int>();
foreach(var item in integers)
{
    if(!result.Any())
    {
        result.Add(item);
    }
    else if(result[result.Count() - 1] != item)
    {
        result.Add(item);
    }
}

Reduce stacks of duplicates in an array into only one of them in c#

2 Answers2