Changes to inplace operations for large dataframes.

plot_transmission_timeline.py

 
     # Frequency
     stats_df = transmission_df \
-        .groupby("goodput", inplace=True)["goodput"] \
-        .agg("count", inplace=True) \
-        .pipe(pd.DataFrame, inplace=True) \
+        .groupby("goodput")["goodput"] \
+        .agg("count") \
+        .pipe(pd.DataFrame) \
         .rename(columns={"goodput": 'frequency'}, inplace=True)
 
     # PDF