def plot_dendogram(df_one_race, filename):

    # Data prep
    df = df_one_race.drop(index_list, axis=1)
    X = df.as_matrix(columns=None)
    Z = linkage(X, 'ward')

    # call dendrogram to get the returned dictionary (plotting parameters can be ignored at this point)
    R = dendrogram(
                Z,
                no_plot=True,
                )

    # create a label dictionary
    labels = df_one_race.driverRef
    temp = {R["leaves"][ii]: labels[ii] for ii in range(len(R["leaves"]))}
    def llf(xx):
        return "{}".format(temp[xx])

    dendrogram(
        Z,
        leaf_label_func=llf,
        leaf_rotation=90.,
        leaf_font_size=8.,
    )

    plt.title('Dendrogram')
    plt.xlabel('Drivers')
    plt.ylabel('Distance')
    plt.savefig(directory+filename, bbox_inches='tight', facecolor='w', transparent=False, pad_inches = 0.5)
    plt.show()