title: counting names based on value column pandas
body: <p>For the following dataframe, based on colorsnames covered over two plants, looking to create new column that counts 1 if color exists in both plants and 0 if this is not the case:</p>
  <p>df:</p>
  <pre><code>Color      Plant
  green1     1
  blue2      1
  red1       1
  purple6    2
  blue2      1
  blue3      2
  green1     2
  green1     1
  red2       1
  purple6    1       
  </code></pre>
  <p>Desired output:</p>
  <pre><code>Color      Plant   Spillover
  green1     1       1
  blue2      1       0
  red1       1       0
  purple6    2       1
  blue2      1       0
  blue3      2       0
  green1     2       1
  green1     1       1
  red2       1       0
  purple6    1       1
  </code></pre>