feat: Implement ST_LENGTH geography function

bigframes/bigquery/__init__.py

@@ -32,6 +32,7 @@
     st_difference,
     st_distance,
     st_intersection,
+    st_length,
 )
 from bigframes.bigquery._operations.json import (
     json_extract,
@@ -58,6 +59,7 @@
     "st_difference",
     "st_distance",
     "st_intersection",
+    "st_length",
     # json ops
     "json_extract",
     "json_extract_array",

bigframes/bigquery/_operations/__init__.py

@@ -11,3 +11,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
+from .geo import st_length
+
+__all__ = [
+    "st_length",
+]

bigframes/bigquery/_operations/geo.py

@@ -380,3 +380,59 @@ def st_intersection(
             each aligned geometry with other.
     """
     return series._apply_binary_op(other, ops.geo_st_intersection_op)
+
+
+def st_length(
+    series: Union[bigframes.series.Series, bigframes.geopandas.GeoSeries],
+) -> bigframes.series.Series:
+    """
+    Computes the length of the input GEOGRAPHY.
+
+    For LINESTRING, MULTILINESTRING, POLYGON, MULTIPOLYGON the length is the
+    great-circle length of their boundaries on the WGS84 spheroid, in meters.
+    For POINT, MULTIPOINT, and empty GEOGRAPHYs, the length is 0.
+
+    .. note::
+        BigQuery's Geography functions, like `st_length`, interpret the geometry
+        data type as a point set on the Earth's surface. A point set is a set
+        of points, lines, and polygons on the WGS84 reference spheroid, with
+        geodesic edges. See: https://cloud.google.com/bigquery/docs/geospatial-data
+
+    **Examples:**
+
+        >>> import bigframes.geopandas
+        >>> import bigframes.pandas as bpd
+        >>> import bigframes.bigquery as bbq
+        >>> from shapely.geometry import Polygon, LineString, Point
+        >>> bpd.options.display.progress_bar = None
+
+        >>> series = bigframes.geopandas.GeoSeries(
+        ...         [
+        ...             LineString([(0, 0), (1, 1), (0, 1)]),
+        ...             Polygon([(0.0, 0.0), (0.1, 0.1), (0.0, 0.1)]),
+        ...             Point(0, 1),
+        ...         ]
+        ... )
+        >>> series
+        0                        LINESTRING (0 0, 1 1, 0 1)
+        1              POLYGON ((0 0, 0.1 0.1, 0 0.1, 0 0))
+        2                                       POINT (0 1)
+        dtype: geometry
+
+        >>> bbq.st_length(series)
+        0    314420.232042
+        1    374483.073393
+        2         0.0
+        dtype: Float64
+
+    Args:
+        series (bigframes.pandas.Series | bigframes.geopandas.GeoSeries):
+            A series containing geography objects.
+
+    Returns:
+      bigframes.pandas.Series:
+          Series of float representing the lengths in meters.
+    """
+    series = series._apply_unary_op(ops.geo_st_length_op)
+    series.name = None
+    return series

bigframes/geopandas/geoseries.py

@@ -30,6 +30,12 @@ def __init__(self, data=None, index=None, **kwargs):
             data=data, index=index, dtype=geopandas.array.GeometryDtype(), **kwargs
         )
 
+    @property
+    def length(self):
+        raise NotImplementedError(
+            "GeoSeries.length is not yet implemented. Please use bigframes.bigquery.st_length(geoseries) instead."
+        )
+
     @property
     def x(self) -> bigframes.series.Series:
         series = self._apply_unary_op(ops.geo_x_op)

bigframes/operations/__init__.py

@@ -98,6 +98,7 @@
     geo_st_geogfromtext_op,
     geo_st_geogpoint_op,
     geo_st_intersection_op,
+    geo_st_length_op,
     geo_x_op,
     geo_y_op,
     GeoStDistanceOp,
@@ -385,6 +386,7 @@
     "geo_st_geogfromtext_op",
     "geo_st_geogpoint_op",
     "geo_st_intersection_op",
+    "geo_st_length_op",
     "geo_x_op",
     "geo_y_op",
     "GeoStDistanceOp",

bigframes/operations/geo_ops.py

@@ -54,6 +54,13 @@
     name="geo_st_geogpoint", type_signature=op_typing.BinaryNumericGeo()
 )
 
+geo_st_length_op = base_ops.create_unary_op(
+    name="geo_st_length",
+    type_signature=op_typing.FixedOutputType(
+        dtypes.is_geo_like, dtypes.FLOAT_DTYPE, description="geo-like"
+    ),
+)
+
 geo_x_op = base_ops.create_unary_op(
     name="geo_x",
     type_signature=op_typing.FixedOutputType(