get rid of pandas warnings

Author: Susan Vanderplas

part-gen-prog/03-data-struct.qmd

@@ -276,10 +276,10 @@ weekdays = pd.Series(['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'F
 
 ```{python series-pandas-4, error = T}
 # access individual objs
-weekdays[0]
-weekdays[1]
-weekdays['S']
-weekdays['Sat']
+weekdays.iloc[0]
+weekdays.iloc[1]
+weekdays.loc['S']
+weekdays.loc['Sat']
 
 # access the index
 weekdays.index