title: Fill matrix with value by searching for index and column names in other DataFrame
body: <p>I have a &quot;empty&quot; data frame looking as follows:</p>
  <pre><code>        6807    6809    5341
  126293  nan     nan     nan
  126294  nan     nan     nan     
  126295  nan     nan     nan     
  </code></pre>
  <p>The column names give me an <code>name_id</code> whereas the index values give me a <code>file_id</code>. Now I want to search for the <code>file_id</code> and the <code>name_id</code> in separate pandas data frames named <code>pro</code>, <code>cont</code>, and <code>neutral</code> which look like this:</p>
  <pre><code>    file_id name_id
  0   126293  7244
  1   126293  4978
  2   126293  5112
  3   126293  6864
  </code></pre>
  <p>If I find the <code>file_id</code>and <code>name_id</code>in the <code>pro</code>dataframe I want to fill the empty data frame cell above with <code>1</code>, when found in <code>cont</code> then <code>-1</code> when in <code>neutral</code>, then the value entered into the matrix should be <code>0</code>. Giving me a result like this, e.g.:</p>
  <pre><code>        6807    6809    5341
  126293  1       -1     0
  126294  0       -1     0        
  126295  1       -1     1        
  </code></pre>
  <p>Does someone know how to get this done?</p>