citycsv in gen_hw_set and renames the columns for
latitude and longitude lat and lon, based on
the user's selections in lat_lon_colnames for
gen_hw_set. If there are extra columns besides those and the
city column, this function removes them.
process_cities_file(cities, lat_lon_colnames)city with a
unique identifier for each city in the study, as well as columns for
latitude and longitude. Other columns may be included in the dataset, but
will not be passed through to later code.citycsv dataframe for latitude (first vector element) and
longitude (second vector element)