title: How to groupBy a list and map the result to another list
body: <p>I have the following piece of code:</p>
  
  <pre><code> public List&lt;myTask&gt; MyTask { get; set; }
  
  
   public class myTask
  {
      public List&lt;int&gt; ID { get; set; }
      public List&lt;DateTime&gt; Date { get; set; }
      public Decimal Total { get; set; }
   }
   List&lt;myTask&gt; tempTask = new List&lt;myTask&gt;();
   MyTask = new List&lt;myTask&gt;();
  </code></pre>
  
  <p>I want to do something as follows but having the error message:</p>
  
  <pre><code>MyTask = tempTask.GroupBy(x =&gt; x.Date);
  </code></pre>
  
  <blockquote>
    <p>Error 1   Cannot implicitly convert type
    'System.Collections.Generic.IEnumerable,MvcUI.Models.MyTask>>'
    to 'System.Collections.Generic.List'. An explicit
    conversion exists (are you missing a cast?)</p>
  </blockquote>
  
  <hr>
  
  <p>Edited Code:</p>
  
  <p>I have tried to add the code:  </p>
  
  <pre><code>var newtempTask = tempTask.GroupBy(x =&gt; x.Date, (Date, values) =&gt;
  
  
   new
                      {
                          ID = values.Select(x =&gt; x.ID).ToList(),
                          Date = values.Select(x =&gt; x.Date).ToList(), Total=values.Select(x =&gt; x.Date).ToList() 
                                                                            }); and then 
          foreach (var newitem in newtempTask)
          {
              MyTask.Add(new MyTask
                             {
                                 ID = newitem.ID,
                                 Date= newitem.Date,Total = newitem.Total
                             });}
  </code></pre>
  
  <blockquote>
    <p>I have tried to add the code, please see the above edited code. I am having the error message, Error 7 Cannot implicitly convert type 'System.Collections.Generic.List>' to 'System.Collections.Generic.List'</p>
  </blockquote>