 distance between two 1-D arrays.

The Euclidean distance between 1-D arrays `u` and `v`, is defined as

.. math::

   {\|u-v\|}_2

   \left(\sum{(w_i |(u_i - v_i)|^2)}\right)^{1/2}

Parameters
----------
u : (N,) array_like
    Input array.
v : (N,) array_like
    Input array.
w : (N,) array_like, optional
    The weights for each value in `u` and `v`. Default is None,
    which gives each value a weight of 1.0

Returns
-------
euclidean : double
    The Euclidean distance between vectors `u` and `v`.

Examples
--------
>>> from scipy.spatial import distance
>>> distance.euclidean([1, 0, 0], [0, 1, 0])
1.4142135623730951
>>> distance.euclidean([1, 1, 0], [0, 1, 0])
1.0

r(