How to filter duplicate list items

Question

i have list of items IList with data that looks list this:

GenId     TestMode
  1          0
  1          1
  3          0
  3          1
  4        NULL
  2        NULL

i want to remove the index of GenId from my list that have TestMode == 0 if the same GenId has a TestMode == 1.

does someone have a terse way of doing this?

Ryan Brunner · Accepted Answer · 2009-11-09 16:48:57Z

1

LINQ is very good at running operations against collections of objects. The following query should give you what you are looking for:

var query = list.Where(i => i.TestMode == 1 || 
                   !list.Exists(i2 => i2.GenId == i.GenId && i2.TestMode == 1));

foreach (var item in query) {
    // do something with items.
}

What this does is looks for an item where TestMode is equal to 1 (and includes if so), or otherwise checks to see if there is another element where TestMode is equal to 1, and excludes if that records exists.

answered Nov 9, 2009 at 16:48

Ryan Brunner

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