ch03 comments - DE-9IM patterns

03-spatial-operations.qmd

@@ -220,10 +220,15 @@ Despite their mathematical origins, topological relations can be understood intu
 @fig-spatial-relations shows a variety of geometry pairs and their associated relations.
 The third and fourth pairs in @fig-spatial-relations (from left to right and then down) demonstrate that, for some relations, order is important: while the relations equals, intersects, crosses, touches and overlaps are symmetrical, meaning that if `x.relation(y)` is true, `y.relation(x)` will also be true, relations in which the order of the geometries are important such as contains and within are not.
 <!-- jn: maybe put the DE-9IM explanation in a block. Also -- is there any python tool to use it? If so, maybe we should mention it... -->
-Notice that each geometry pair has a ["DE-9IM"](https://en.wikipedia.org/wiki/DE-9IM) string such as FF2F11212.
+<!-- md: good ideas, added both! -->
+
+::: callout-note
+Notice that each geometry pair has a ["DE-9IM"](https://en.wikipedia.org/wiki/DE-9IM) string such as `FF2F11212`.
 DE-9IM strings describe the dimensionality (0=points, 1=lines, 2=polygons) of the pairwise intersections of the interior, boundary, and exterior, of two geometries (i.e., nine values of 0/1/2 encoded into a string).
 This is an advanced topic beyond the scope of this book, which can be useful to understand the difference between relation types, or define custom types of relations.
-See the [DE-9IM strings](https://r.geocompx.org/spatial-operations#de-9im-strings) section in Geocomputation with R [@lovelace_geocomputation_2019].
+See the [DE-9IM strings](https://r.geocompx.org/spatial-operations#de-9im-strings) section in Geocomputation with R [@lovelace_geocomputation_2019]. 
+Also note that the **shapely** package contains the `.relate` and `.relate_pattern` [methods](https://shapely.readthedocs.io/en/stable/manual.html#de-9im-relationships), for derive and test for DE-9IM patterns, respectively.
+:::
 
 ![Topological relations between vector geometries, inspired by Figures 1 and 2 in Egenhofer and Herring (1990). The relations for which the `x.relation(y)` is true are printed for each geometry pair, with `x` represented in pink and `y` represented in blue. <!--toDo: move the used images from geocompr to the geocompy repo (this will make it more stable)--> The nature of the spatial relationship for each pair is described by the Dimensionally Extended 9-Intersection Model string.](https://r.geocompx.org/04-spatial-operations_files/figure-html/relations-1.png){#fig-spatial-relations}