title: Use other pairwise distance metrics in scikit-learn for KNN besides p-norm
body: <p>For <a href="http://scikit-learn.org/dev/modules/neighbors.html#unsupervised-nearest-neighbors" rel="nofollow">scikit-learn's KNN package</a>, can one specify a pairwise distance metric (from the package <code>sklearn.metrics.pairwise</code>) that isn't the p-norm, or Minkowski distance? For example, could I use the <a href="http://scikit-learn.org/dev/modules/generated/sklearn.metrics.pairwise.rbf_kernel.html#sklearn.metrics.pairwise.rbf_kernel" rel="nofollow">RBF kernel</a>? Or even the <a href="http://scikit-learn.org/dev/modules/generated/sklearn.metrics.pairwise.pairwise_distances.html#sklearn.metrics.pairwise.pairwise_distances" rel="nofollow">cosine distance</a>?</p>