Fix bug in k-means example.
Fix bug in k-means example.

woparry/spire,tixxit/spire,siddhartha-gadgil/spire,adampingel/spire,codeaudit/spire,tixxit/spire,non/spire,AlecZorab/spire,guersam/spire,rklaehn/spire,adampingel/spire,AlecZorab/spire,codeaudit/spire,kevinmeredith/spire,rklaehn/spire,siddhartha-gadgil/spire,JackSullivan/spire,kevinmeredith/spire,JackSullivan/spire,non/spire,guersam/spire,woparry/spire