Ensures that scores is stored as a numpy array and checks that all
    values are finite.

def verify_scores(scores):
    """Ensures that scores is stored as a numpy array and checks that all
    values are finite.
    """
    scores = np.array(scores, copy=False)
    if np.any(~np.isfinite(scores)):
        raise ValueError("scores contains invalid values. " +
                         "Please check that all values are finite.")
    if scores.ndim == 1:
        scores = scores[:,np.newaxis]
    return scores