title: How to create a new col in the dataframe if a symbol exists in the first col
body: <p>I have a data frame with some text read in from a txt file the column names are <code>FEATURE</code> and <code>SENTENCE</code>. Within the <code>FEATURE</code> col there is some text that has a <code>+</code> or a <code>-</code> symbol somewhere in the txt.</p>
  <p>How can I create a new col called <code>RESULTS</code> and:</p>
  <ul>
  <li>if <code>+</code> exists in the <code>FEATURE</code> row then the new col will have a <code>positive</code></li>
  <li>and if <code>-</code> exists the new <code>RESULTS</code> will have a <code>negative</code>
  but if both signs exist then the <code>RESULTS</code> will have <code>neutral</code></li>
  </ul>
  <p>I tried to use the <code>np.where</code> but failed.
  My data types for the <code>FEATURE</code> is string.</p>
  <p>Please see a sample of the data:</p>
  <pre><code>{'FEATURE': {0: '[NA] this is not a feature.',
    1: 'entertainment value[+8]',
    2: 'image quality[+6]',
    3: 'extras [-2]',
    4: 'a list cast[+2],oscar winners[+1]'},
    'SENTENCE': {0: &lt;NA&gt;,
    1: 'starwars trilogy',
    2: ' good for an old dvd',
    3: 'dvd no had extra features',
    4: ' good cast'}}
  </code></pre>