Coding question

AI & Machine learning
1

X_train=np.array(X.iloc[:-test_size])

y_train=np.array(y[:-test_size])

X_test=np.array(X.iloc[-test_size:])

y_test=np.array(y[-test_size:])


  • I know that a -ve sign means taking the last of something. But is it really necessary to put a -ve sign in front of the test size?
  • Why does X feature dataset makes use of iloc while y target dataset doesn't?



     
2

Hi Sean!



This code snippet is from which course/unit?



Thanks.

3

It's from neural networks in trading: DNN trading strategy

4

Hi Sean,



Please refer to the screenshot below:






  1. The X is a DataFrame and y is an array. "iloc" is a good way to extract rows from the DataFrame.
  2. The method without iloc also works on DataFrame , and the output is identical as can be seen in the code snippet above.
  3. The example of index slicing is shown which will help you understand that [-size:] chooses the last "size" number objects from the list.
  4. The [:-size] chooses the numbers except the last "size" objects in the list.



    Hope this helps!