Get distinct output from an array

Question

From a string array

string[] str1={"u1-u2","u1-u2","u1-u4","u4-u1"};
string[] str2 = str1.Distinct().ToArray();

Distinct elements in a arry is:"u1-u2","u1-u4","u4-u1"

But i have to get distinct output like this: "u1-u2","u1-u4".

so please help me out

Why exactly does the output have to look like that? Are the pairs unordered (so x-y is always the same as y-x)? — svick
– svick, Commented Apr 18, 2014 at 9:18

Ulugbek Umirov · Accepted Answer · 2014-04-18 09:17:21Z

2

You can do like this:

string[] output = str1.Select(s => new { Value = s, NormalizedValue = string.Join("-", s.Split('-').OrderBy(_ => _)) })
                      .GroupBy(p => p.NormalizedValue)
                      .Select(g => g.OrderBy(p => p.Value).First().Value)
                      .ToArray();

edited Apr 18, 2014 at 9:17

answered Apr 18, 2014 at 7:56

Ulugbek Umirov

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Community · Accepted Answer · 2017-05-23 10:32:26Z

1

You can convert all values to their normalized form and the call Distinct() on that:

string[] output = str1.Select(string.Join("-", s.Split('-').OrderBy(x => x)))
                      .Distinct()
                      .ToArray();

(This is based on the code from Ulugbek Umirov's answer.)

edited May 23, 2017 at 10:32

CommunityBot

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answered Apr 18, 2014 at 9:23

svick

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3 Comments

Ulugbek Umirov Over a year ago

I did like that in first version of answer, but it causes the following problem: {"u4-u1"} => {"u1-u4"}.

svick Over a year ago

If you consider u4-u1 and u1-u4 to be equal, then you also shouldn't care which one is going to be in the output. But the problem certainly isn't specified well enough to know that for sure.

Ulugbek Umirov Over a year ago

Yes, but it's rather strange to see in output the value you don't have in the input.

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