def view_label_matrix(L, colorbar=True):
    """Display an [n, m] matrix of labels"""
    L = L.todense() if sparse.issparse(L) else L
    plt.imshow(L, aspect="auto")
    plt.title("Label Matrix")
    if colorbar:
        labels = sorted(np.unique(np.asarray(L).reshape(-1, 1).squeeze()))
        boundaries = np.array(labels + [max(labels) + 1]) - 0.5
        plt.colorbar(boundaries=boundaries, ticks=labels)
    plt.show()