定义：

Stack arrays in sequence horizontally (column wise).

Take a sequence of arrays and stack them horizontally to make a single array. Rebuild arrays divided by .

This function continues to be supported for backward compatibility, but you should prefer np.concatenate or np.stack. The np.stack function was added in NumPy 1.10.

　　用法：

>>> a = np.array((1,2,3))>>> b = np.array((2,3,4))>>> np.hstack((a,b))array([1, 2, 3, 2, 3, 4])>>> a = np.array([[1],[2],[3]])>>> b = np.array([[2],[3],[4]])>>> np.hstack((a,b))array([[1, 2],       [2, 3],       [3, 4]])