title: Pandas DataFrame to Dictionary conversion
body: <p>I have a dataframe, which I want to convert to a dictionary in such a way that col1 becomes the key and col2 becomes the value. Also, there can be multiple occurrences of a value in 1st col, in which case  I want to store the counts in the form of a list corresponding to that value of col1 as key.
  So basically how can I perform this conversion -
  <br><br>
   area  count</p>
  
  <p>10  &nbsp;    7 <br>
   10  &nbsp;    3 <br>
   10  &nbsp;    1 <br>
   20  &nbsp;    5 <br>
   30  &nbsp;    2 <br>
   30  &nbsp;    1 <br>
   40  &nbsp;    3 <br></p>
  
  <p>{ <br>
  '10' : [7,3,1],<br>'20' : '5',<br>'30' : [2,1],<br>'40' : 3 
  <br>}</p>
  
  <p>Thanks in advance!</p>