Docstring done

docs/graphs/edge_attributes.rst

@@ -4,7 +4,7 @@
  Edges - Attributes
 ####################
 
-There are 2 main edge attributes implemented in the `anemoi-graphs`
+There are few edge attributes implemented in the `anemoi-graphs`
 package:
 
 *************
@@ -44,3 +44,47 @@ latitude and longitude coordinates of the source and target nodes.
        attributes:
          edge_length:
             _target_: anemoi.graphs.edges.attributes.EdgeDirection
+
+*********************
+ Attribute from Node
+*********************
+
+Attributes can also be copied from nodes to edges. This is done using
+the `AttributeFromNode` base class, with specialized versions for source
+and target nodes.
+
+*************
+ From Source
+*************
+
+This attribute copies a specific property of the source node to the
+edge.
+
+.. code:: yaml
+
+   edges:
+     - source_name: ...
+       target_name: ...
+       edge_builders: ...
+       attributes:
+          attribute_name:
+            _target_: anemoi.graphs.edges.attributes.AttributeFromSourceNode
+            node_attr_name: "attribute_name"
+
+*************
+ From Target
+*************
+
+This attribute copies a specific property of the target node to the
+edge.
+
+.. code:: yaml
+
+   edges:
+     - source_name: ...
+       target_name: ...
+       edge_builders: ...
+       attributes:
+         attribute_name:
+            _target_: anemoi.graphs.edges.attributes.AttributeFromTargetNode
+            node_attr_name: "attribute_name"

src/anemoi/graphs/edges/attributes.py

@@ -204,6 +204,7 @@ def get_raw_values(self, graph: HeteroData, source_name: str, target_name: str)
         assert hasattr(graph[node_name], self.node_attr_name)
         return graph[node_name][self.node_attr_name].numpy()[edge_index[self.idx]]
 
+
 class AttributeFromSourceNode(AttributeFromNode):
     """
     Copy an attribute of the source node to the edge.