title: How to convert R dataframe to Json in name/value pair?
body: <p>I have the following R data frame:</p>
  
  <pre><code>        Values
  Type1   123
  Type2   4565
  Type3   7812
  </code></pre>
  
  <p>I expect the JSON output to be </p>
  
  <pre><code>{"Type1":123, "Type2":4565, "Type3":7812}
  </code></pre>
  
  <p>The number field can w/wo quote</p>
  
  <p>I used jsonlite toJSON, the output is:</p>
  
  <pre><code>[{"Values":123,"_row":"Type1"}, 
   {"Values": 4565,"_row":"Type2"}, 
   {"Values": 7812,"_row":"Type3"}]
  </code></pre>