title: Using One Hot Encoder
body: <p>I have two questions regarding the scikit-learn OHE method :</p>
  <ol>
  <li><p>why one hot encoder doesn't accept one dimensional data while it works perfectly if we just reshaped our data to <code>(nrows,1)</code>?</p>
  </li>
  <li><p>what does (drop=first, binary, etc.) actually does and what will happen if we just set the value to None?</p>
  </li>
  </ol>