title: Error in UseMethod("group_by_") : no applicable method for 'group_by_' applied to an object of class "character"
body: <p>This is the code: </p>
  
  <pre><code>PRICE &lt;- as.vector(my.data[,"PRICE"])
  ADDRESS_CITY_NAME &lt;- as.vector(my.data[,"ADDRESS_CITY_NAME"])
  
  my.data &lt;- data.frame(ADDRESS_CITY_NAME,log(UNITS), log(PRICE))
  
  my.data %&gt;%
    +group_by(ADDRESS_CITY_NAME)%&gt;%
    +do(tidy(lm(UNITS~PRICE, data=my.data))
  </code></pre>
  
  <p>The data I used (part of it):</p>
  
  <pre><code>287      INDEPENDENCE  4.1108739  0.42526774
  288      INDEPENDENCE  4.1431347  0.47000363
  289      INDEPENDENCE  4.2766661  0.17395331
  290      INDEPENDENCE  4.0604430  0.46373402
  291          LOVELAND  4.3820266  0.38526240
  292          LOVELAND  4.2626799  0.42526774
  293          LOVELAND  4.1271344  0.51282363
  294          LOVELAND  4.8040210  0.43178242
  295          LOVELAND  4.1896547  0.37843644
  296          LOVELAND  4.2766661  0.32930375
  297          LOVELAND  4.4543473  0.39204209
  298          LOVELAND  4.3820266  0.39877612
  299          LOVELAND  3.7841896  0.43178242
  </code></pre>
  
  <p>I keep getting the error: 
  Error in UseMethod("group_by_") :    no applicable method for 'group_by_' applied to an object of class "character" </p>