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POSelecting "custom distinct" items from a List using LINQ
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  1. POSelecting "custom distinct" items from a List using LINQ
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    copied!<p>I have a generic List of Policy objects.</p> <p>The list contains the following data</p> <pre><code>id policyNumber policySequence otherData 1 101 1 aaaa 2 101 2 bbbb 3 101 3 cccc 4 102 1 dddd 5 103 1 eeee 6 103 2 ffff </code></pre> <p>I want to select the one row containing the highest policySequence for each policyNumber, so that I end up with the following:</p> <pre><code>id policyNumber policySequence created 3 101 3 cccc 4 102 1 dddd 6 103 2 ffff </code></pre> <p>I have a solution below using a foreach, but was wondering if there was an easier, cleaner way to do this in LINQ?</p> <pre><code>class Program { static void Main(string[] args) { List&lt;Policy&gt; policyList = new List&lt;Policy&gt; { new Policy {id = 1, policyNumber = 101, policySequence = 1, otherData = "aaaa"}, new Policy {id = 2, policyNumber = 101, policySequence = 2, otherData = "bbbb"}, new Policy {id = 3, policyNumber = 101, policySequence = 3, otherData = "cccc"}, new Policy {id = 4, policyNumber = 102, policySequence = 1, otherData = "dddd"}, new Policy {id = 5, policyNumber = 103, policySequence = 1, otherData = "eeee"}, new Policy {id = 6, policyNumber = 103, policySequence = 2, otherData = "ffff"} }; List&lt;Policy&gt; filteredPolicyList = new List&lt;Policy&gt;(); foreach(var policy in policyList) { if(!filteredPolicyList.Exists(x =&gt; x.policyNumber == policy.policyNumber)) { filteredPolicyList.Add(policy); } else { var currentPolicyInFilteredList = filteredPolicyList.Where(x =&gt; x.policyNumber == policy.policyNumber).First(); if (policy.policySequence &gt; currentPolicyInFilteredList.policySequence) { filteredPolicyList.Remove(currentPolicyInFilteredList); filteredPolicyList.Add(policy); } } } } } public class Policy { public int id; public int policyNumber; public int policySequence; public string otherData; } </code></pre>
 

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