Changes goodput calculation.

plot_transmission_timeline.py

@@ -149,7 +149,7 @@ if __name__ == "__main__":
 
     # key for columns and level for index
     goodput_df = transmission_df["payload_size"].groupby(pd.Grouper(level="datetime", freq="{}s".format(args.interval))).sum().dropna()
-    print(goodput_df)
+    print(goodput_df["payload_size"])
     exit()