Fix grouper issue.

cdf_compare.py

@@ -200,6 +200,7 @@ if __name__ == "__main__":
     # Plot sRTT CDF
     legend = list()
     plot_cdf(transmission_df_list[0]["df"], "srtt")
+    legend.append(transmission_df_list[0]["cc_algo"])
     for i in range(1, len(transmission_df_list)):
         plot_cdf(transmission_df_list[i]["df"], "srtt", axis=plt.gca())
         legend.append(transmission_df_list[i]["cc_algo"])
@@ -215,6 +216,7 @@ if __name__ == "__main__":
     # Plot goodput CDF
     legend = list()
     plot_cdf(transmission_df_list[0]["df"], "goodput")
+    legend.append(transmission_df_list[0]["cc_algo"])
     for i in range(1, len(transmission_df_list)):
         plot_cdf(transmission_df_list[i]["df"], "goodput", axis=plt.gca())
         legend.append(transmission_df_list[i]["cc_algo"])