Fix convergenceWarning

[chenxinye]

I fix a bug arisen from the number unique pieces is more than the specified number of kmeans clusters:

ConvergenceWarning: Number of distinct clusters (6) found smaller than n_clusters (9). Possibly due to duplicate points in X.
kmeans = KMeans(n_clusters=k, tol=0, random_state=0).fit(data)

ConvergenceWarning: Number of distinct clusters (8) found smaller than n_clusters (9). Possibly due to duplicate points in X.
kmeans = KMeans(n_clusters=k, tol=0, random_state=0).fit(data)
file: ShakeGestureWiimoteZ_TEST.tsv