title: Grouping and summarizing by keeping other columns in R
body: <p>I have a dataframe which I am grouping using the group_by function, and summarizing it with using the summarize function in R. </p>
  
  <pre><code>MM_group&lt;-group_by(SYC,Method,Maturity)
  </code></pre>
  
  <p>My dataset looks like this,</p>
  
  <pre><code> Year           Group  County Seed.Brand Seed.Variety Seed.Maturity
  1 2014 Group 0 No-till Yankton     Asgrow       AG0832           0.8
  2 2014 Group 0 No-till   Brown     Asgrow       AG0934           0.9
  3 2014 Group 0 No-till   Brown     Asgrow       AG0934           0.9
  4 2014 Group 0 No-till   Brown     Asgrow       AG0934           0.9
  5 2014 Group 0 No-till   Brown    Pioneer        90Y90           0.9
  6 2014 Group 0 No-till   Brown     Asgrow       AG0934           0.9
  
  Yield  Method Maturity digits
  1 73.23 No-till        0      0
  2 65.14 No-till        0      0
  3 63.63 No-till        0      0
  4 61.57 No-till        0      0
  5 60.20 No-till        0      0
  </code></pre>
  
  <p>I am grouping by Method &amp; Maturity. I am trying to get County and Year for maximum yield for the Method &amp; Maturity combination.</p>
  
  <p>I have done the following:</p>
  
  <pre><code>summarize(MM_group,Max_Yield=max(Yield))
  
         Method Maturity Max_Yield
             &lt;chr&gt;    &lt;chr&gt;     &lt;dbl&gt;
  1      Irrigated        0    69.600
  2      Irrigated        1    86.013
  3      Irrigated        2    88.750
  4      Irrigated        3    79.650
  5        No-till        0    79.470
  6        No-till        1    79.856
  7        No-till        2    85.860
  8        No-till        3    68.530
  9  Non-irrigated        0    83.210
  10 Non-irrigated        1    81.916
  11 Non-irrigated        2   103.740
  12 Non-irrigated        3    94.410
  </code></pre>
  
  <p>But, this doesn't give me the county name and year. I know I can use cbind or joins to get that data but wondering if there is another easier way of doing this.</p>
  
  <p>Expected Output:</p>
  
  <pre><code>          Method Maturity Max_Yield  Year                  Group
             &lt;chr&gt;    &lt;chr&gt;     &lt;dbl&gt; &lt;int&gt;                 &lt;fctr&gt;
  1      Irrigated        0    69.600  2012 Group 0 or 1 Irrigated
  2      Irrigated        1    86.013  2012 Group 0 or 1 Irrigated
  3      Irrigated        2    88.750  2013 Group 2 or 3 Irrigated
  4      Irrigated        3    79.650  2013 Group 2 or 3 Irrigated
  5        No-till        0    79.470  2013        Group 0 No-till
  6        No-till        1    79.856  2012        Group 1 No-till
  7        No-till        2    85.860  2013        Group 2 No-till
  8        No-till        3    68.530  2014        Group 3 No-till
  9  Non-irrigated        0    83.210  2013  Group 0 Non-irrigated
  10 Non-irrigated        1    81.916  2012  Group 1 Non-irrigated
  11 Non-irrigated        2   103.740  2014  Group 2 Non-irrigated
  12 Non-irrigated        3    94.410  2014  Group 3 Non-irrigated 
  </code></pre>