cartopy additions

08-read-write-plot.qmd

@@ -114,7 +114,7 @@ These provide interfaces to one or more spatial libraries or geoportals and aim
 
 Each data package has its own syntax for accessing data. 
 This diversity is demonstrated in the subsequent code chunks, which show how to get data using three packages from @tbl-data-packages. 
-Country borders are often useful and these can be accessed with the ne_countries() function from the rnaturalearth package as follows:
+Country borders are often useful and these can be accessed with the `cartopy.io.shapereader.natural_earth` function from the `cartopy` package, as follows. 
 
 ```{python}
 import cartopy
@@ -127,10 +127,23 @@ counties = gpd.read_file(filename)
 counties
 ```
 
+The layer of counties is plotted in @fig-ne-counties:
+
 ```{python}
+#| label: fig-ne-counties
+#| fig-cap: US counties, downloaded from the Natural Earth Data website using package `cartopy`
+
 counties.plot();
 ```
 
+Other layers can be accessed the same way: 
+
+* you need to locate the `resolution`, `category`, and `name` of the requested dataset, then 
+* run the `cartopy.io.shapereader.natural_earth`, which downloads the file(s) and returns the path, and
+* read the file into the Python environment, e.g., using `gpd.read_file`
+
+This is an alternative approach to "directly" downloading files (@sec-retrieving-open-data).
+
 ## Geographic web services
 
 To complete...