title: group by average on a list of objects in C#
body: <p>I have a list of objects where object looks like below</p>
  
  <pre><code>public class Sample
  {
      public DateTime _dt;
      public decimal _d;
      public decimal_value;
  }
  </code></pre>
  
  <p>I want a list grouped by year and month of a date and _d values with _value averaged.</p>
  
  <p>So if for month Jan, list has </p>
  
  <pre><code>one set of 31 values with _d =1, 
  one set of 31 values with _d =5
  </code></pre>
  
  <p>result list of Sample will have two values </p>
  
  <pre><code>1/1/2016 ,_d = 1 and average of _value
  1/1/2016 ,_d = 5 and average of _value
  </code></pre>