title: why 'The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() ' happened
body: <p>1.I was trying to implement a data normalization algorithm. The input data &quot;data_train_set&quot; which  is NumPy array</p>
  <pre><code>data0 = [(x - min(data_train_set))/(max(data_train_set) - min(data_train_set)) for x in data_train_set]
  </code></pre>
  <p>2.I do not know where should I put .any or.all</p>