add Expression.name

Author: MarcoGorelli

spec/API_specification/dataframe_api/__init__.py

@@ -44,9 +44,10 @@
 
 def col(name: str) -> Expression:
     """
-    Instantiate an Expression which selects given columns by name.
+    Instantiate an Expression which selects given column by name.
 
-    For example, to only keep rows where column 'species' equals 'setosa', use
+    For example, to select column 'species' and then use it to filter
+    a DataFrame, you could do:
 
     .. code-block::python
 

spec/API_specification/dataframe_api/expression_object.py

@@ -72,16 +72,9 @@ def __len__(self) -> Expression:
         Return the number of rows.
         """
 
-    def get_rows(self: Expression, indices: Expression) -> Expression:
-        """
-        Select a subset of rows, similar to `ndarray.take`.
-
-        Parameters
-        ----------
-        indices : Expression
-            Positions of rows to select.
-        """
-        ...
+    @property
+    def name(self) -> str:
+        """Return output name of expression."""
 
     def slice_rows(
         self: Expression, start: int | None, stop: int | None, step: int | None