LINQ select non-empty strings

Question

There is a struct S with 2 string fields: A and B.

I want to convert an array of S into string array, containing all non-empty unique As and Bs. What is the most efficient way for that?

Regards,

BrokenGlass · Accepted Answer · 2011-07-31 22:41:29Z

22

var myArray = S.Select( x => new [] { x.A, x.B })
               .SelectMany( x => x)
               .Where( x=> !string.IsNullOrEmpty(x))
               .Distinct()
               .ToArray();

Above only works if the unique constraint is on the resulting collection - if you need a unique constraint on the set of A's and B's the following would work:

var As = S.Select(x => x.A)
          .Where( x=> !string.IsNullOrEmpty(x))
          .Distinct();
var Bs = S.Select(x => x.B)
          .Where( x=> !string.IsNullOrEmpty(x))
          .Distinct();

~~var myArray = new[] { As, Bs }.SelectMany(x => x).ToArray();~~

var myArray = As.Concat(Bs).ToArray();

edited Jul 31, 2011 at 22:41

answered Jul 31, 2011 at 22:25

BrokenGlass

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3 Comments

BrokenGlass Over a year ago

@Joey: Yea, updated - assumption is uniqueness is required on the A's and B's not on the resulting collection, otherwise first approach would be better

Claus Jørgensen Over a year ago

For the record, As.Concat(Bs) would do the same as the SelectMany

BrokenGlass Over a year ago

@Claus Jørgensen: Doh! And its much simpler and readable, edited that in.

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