Format date string correctly

las_outputs.py

@@ -128,7 +128,8 @@ def plot_profiles(profile_name, survey_date, csv_output_dir, graph_loc, ch_limit
     ax = plt.axes()
     for col in profiles.columns:
         profile = profiles.loc[ch_min:, col]
-        date = '{}-{}-{}'.format(survey_date[:4], survey_date[4:6], survey_date[6:])
+        date_str = str(survey_date)
+        date = '{}-{}-{}'.format(date_str[:4], date_str[4:6], date_str[6:])
 
         ax.plot(profile.index, profile, label=date)