Add stream link segmentation module with all four backends

Assigns unique position-based IDs to each stream segment between
junctions, headwaters, and outlets. Supports numpy, cupy, dask+numpy,
and dask+cupy backends.

Author: brendancol

README.md

@@ -247,6 +247,8 @@ In the GIS world, rasters are used for representing continuous phenomena (e.g. e
 | [Flow Accumulation (D8)](xrspatial/flow_accumulation.py) | Counts upstream cells draining through each cell in a D8 flow direction grid | ✅️ | ✅️ | ✅️ | ✅️ |
 | [Watershed](xrspatial/watershed.py) | Labels each cell with the pour point it drains to via D8 flow direction | ✅️ | ✅️ | ✅️ | ✅️ |
 | [Basins](xrspatial/watershed.py) | Delineates drainage basins by labeling each cell with its outlet ID | ✅️ | ✅️ | ✅️ | ✅️ |
+| [Stream Order](xrspatial/stream_order.py) | Assigns Strahler or Shreve stream order to cells in a drainage network | ✅️ | ✅️ | ✅️ | ✅️ |
+| [Stream Link](xrspatial/stream_link.py) | Assigns unique IDs to each stream segment between junctions | ✅️ | ✅️ | ✅️ | ✅️ |
 
 -----------
 

xrspatial/__init__.py

@@ -35,6 +35,7 @@
 from xrspatial.proximity import manhattan_distance  # noqa
 from xrspatial.proximity import proximity  # noqa
 from xrspatial.sink import sink  # noqa
+from xrspatial.stream_link import stream_link  # noqa
 from xrspatial.stream_order import stream_order  # noqa
 from xrspatial.slope import slope  # noqa
 from xrspatial.surface_distance import surface_allocation  # noqa

xrspatial/accessor.py

@@ -87,6 +87,10 @@ def stream_order(self, flow_accum, **kwargs):
         from .stream_order import stream_order
         return stream_order(self._obj, flow_accum, **kwargs)
 
+    def stream_link(self, flow_accum, **kwargs):
+        from .stream_link import stream_link
+        return stream_link(self._obj, flow_accum, **kwargs)
+
     def viewshed(self, x, y, **kwargs):
         from .viewshed import viewshed
         return viewshed(self._obj, x, y, **kwargs)
@@ -317,6 +321,10 @@ def stream_order(self, flow_accum, **kwargs):
         from .stream_order import stream_order
         return stream_order(self._obj, flow_accum, **kwargs)
 
+    def stream_link(self, flow_accum, **kwargs):
+        from .stream_link import stream_link
+        return stream_link(self._obj, flow_accum, **kwargs)
+
     # ---- Classification ----
 
     def natural_breaks(self, **kwargs):