title: 'numpy.ndarray' object has no attribute 'drop'
body: <p>I have a dataset with four inputs named X1, X2, X3, X4. 
  Here I created the lstm model to predict next X1 value with the previous values of four inputs. </p>
  
  <p>Here I changed the time into minutes and then I set the time as index.</p>
  
  <p>Then I created the x_train, x_test , y_test and y_train. Then I wanted to drop the time in x_train and x_test. </p>
  
  <p>I used the code:</p>
  
  <pre><code>data= pd.DataFrame(data,columns=['X1','X2','X3','X4'])
  pd.options.display.float_format = '{:,.0f}'.format
  print(data)
  </code></pre>
  
  <p>data:</p>
  
  <p><a href="https://i.stack.imgur.com/VhOk0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VhOk0.png" alt="enter image description here"></a></p>
  
  <pre><code>y=data['X1'].astype(int)
  cols=['X1', 'X2', 'X3','X4']
  x=data[cols].astype(int)
  
  data=data.values
  scaler_x = preprocessing.MinMaxScaler(feature_range =(0, 1))
  x = np.array(x).reshape ((len(x),4 ))
  x = scaler_x.fit_transform(x)
  scaler_y = preprocessing.MinMaxScaler(feature_range =(0, 1))
  y = np.array(y).reshape ((len(y), 1))
  y = scaler_y.fit_transform(y)
  
  train_end = 80
  x_train=x[0: train_end ,]
  x_test=x[train_end +1: ,]
  y_train=y[0: train_end]
  y_test=y[train_end +1:] 
  x_train=x_train.reshape(x_train.shape +(1,))
  x_test=x_test.reshape(x_test.shape + (1,))
  
  x_train = x_train.drop('time', axis=1)
  x_test = x_test.drop('time', axis=1)
  </code></pre>
  
  <p>Then error :<code>'numpy.ndarray' object has no attribute 'drop'</code></p>
  
  <p>Can any one help me to solve this error?</p>