update data description

preface.qmd

@@ -29,11 +29,10 @@ Links with the vibrant 'R-spatial' community, and other communities such as [Geo
 
 ## Code and sample data
 
-To run the code examples, you can [download](https://github.com/geocompx/geocompy/zipball/master) the ZIP file of the GitHub [repository](https://github.com/geocompx/geocompy/). In the ZIP file, the `ipynb` directory contains the source files of the chapters in Jupyter Notebook format, and the `data` directory contains the sample data files. Place them together as follows to run the code:
+To run the code examples, you can [download](https://github.com/geocompx/geocompy/zipball/master) the ZIP file of the GitHub [repository](https://github.com/geocompx/geocompy/). In the ZIP file, the `ipynb` directory contains the source files of the chapters in Jupyter Notebook format, the `data` directory contains the sample data files, and the `output` directory contains the files created in code examples (some of which are also used as inputs in other code sections). Place them together as follows to run the code:
 
 ```text
 ├── data
-│   ├── absolute_v5.nc
 │   ├── aut.tif
 │   ├── ch.tif
 │   ├── coffee_data.csv
@@ -51,17 +50,51 @@ To run the code examples, you can [download](https://github.com/geocompx/geocomp
 │   ├── us_states.gpkg
 │   ├── world.gpkg
 │   ├── world_wkt.csv
-│   ├── yorkshire.json
 │   ├── zion.gpkg
 │   └── zion_points.gpkg
-├── 01-spatial-data.ipynb
-├── 02-attribute-operations.ipynb
-├── 03-spatial-operations.ipynb
-├── 04-geometry-operations.ipynb
-├── 05-raster-vector.ipynb
-├── 06-reproj.ipynb
-├── 07-read-write.ipynb
-└── 08-mapping.ipynb
+├── output
+│   ├── cycle_hire_xy.csv
+│   ├── dem_agg5.tif
+│   ├── dem_contour.gpkg
+│   ├── dem_resample_maximum.tif
+│   ├── dem_resample_nearest.tif
+│   ├── elev.tif
+│   ├── grain.tif
+│   ├── map.html
+│   ├── ne_10m_airports.cpg
+│   ├── ne_10m_airports.dbf
+│   ├── ne_10m_airports.prj
+│   ├── ne_10m_airports.README.html
+│   ├── ne_10m_airports.shp
+│   ├── ne_10m_airports.shx
+│   ├── ne_10m_airports.VERSION.txt
+│   ├── ne_10m_airports.zip
+│   ├── nlcd_4326_2.tif
+│   ├── nlcd_4326.tif
+│   ├── nlcd_modified_crs.tif
+│   ├── plot_geopandas.jpg
+│   ├── plot_rasterio2.svg
+│   ├── plot_rasterio.jpg
+│   ├── r3.tif
+│   ├── r_nodata_float.tif
+│   ├── r_nodata_int.tif
+│   ├── r.tif
+│   ├── srtm_32612_aspect.tif
+│   ├── srtm_32612_slope.tif
+│   ├── srtm_32612.tif
+│   ├── srtm_masked_cropped.tif
+│   ├── srtm_masked.tif
+│   ├── w_many_features.gpkg
+│   ├── w_many_layers.gpkg
+│   └── world.gpkg
+├── 01-spatial-data.qmd
+├── 02-attribute-operations.qmd
+├── 03-spatial-operations.qmd
+├── 04-geometry-operations.qmd
+├── 05-raster-vector.qmd
+├── 06-reproj.qmd
+├── 07-read-write.qmd
+└── 08-mapping.qmd
 ```
 
 ## Acknowlegements