Improve MF-JSON integration

movingpandas/__init__.py

@@ -13,7 +13,7 @@
     TopDownTimeRatioGeneralizer,
 )
 from .trajectory_collection import TrajectoryCollection  # noqa F401
-from .io import read_mf_json  # noqa F401
+from .io import read_mf_json, read_mf_dict, gdf_to_mf_json  # noqa F401
 from .trajectory_aggregator import TrajectoryCollectionAggregator  # noqa F401
 from .trajectory_splitter import (  # noqa F401
     TrajectorySplitter,

movingpandas/io.py

@@ -4,8 +4,6 @@
 from geopandas import GeoDataFrame
 from pandas import DataFrame
 
-from movingpandas import Trajectory, TrajectoryCollection
-
 
 def gdf_to_mf_json(
     gdf: GeoDataFrame,
@@ -245,6 +243,8 @@ def _get_temporal_properties(data):
 
 
 def _create_traj_from_movingfeature_json(data, traj_id_property, traj_id):
+    from movingpandas import Trajectory
+
     df = _create_geometry(data)
     if traj_id_property:
         traj_id = _get_id_property_value(data, traj_id_property)
@@ -257,6 +257,8 @@ def _create_traj_from_movingfeature_json(data, traj_id_property, traj_id):
 
 
 def _create_trajcollection_from_movingfeaturecollection_json(data, traj_id_property):
+    from movingpandas import TrajectoryCollection
+
     assert (
         traj_id_property is not None
     ), "traj_id_property must be supplied when reading a collection of trajectories"

movingpandas/tests/test_trajectory.py

@@ -1009,6 +1009,13 @@ def test_to_traj_gdf(self):
 
         assert_frame_equal(traj_gdf_wkt, expected_line_gdf_wkt)
 
+    def test_to_mf_json(self):
+        json = self.default_traj_metric.to_mf_json()
+        assert (
+            str(json)
+            == """{'type': 'FeatureCollection', 'features': [{'type': 'Feature', 'properties': {'traj_id': 1, 'value': 1}, 'temporalGeometry': {'type': 'MovingPoint', 'coordinates': [(0.0, 0.0), (6.0, 0.0), (10.0, 0.0)], 'datetimes': [Timestamp('1970-01-01 00:00:00'), Timestamp('1970-01-01 00:00:10'), Timestamp('1970-01-01 00:00:20')]}}]}"""  # noqa F401
+        )
+
     def test_error_due_to_wrong_gdf_index(self):
         with pytest.raises(TypeError):
             df = pd.DataFrame(

movingpandas/tests/test_trajectory_collection.py

@@ -569,3 +569,10 @@ def test_to_traj_gdf_aggregate(self):
         expected_line_gdf = GeoDataFrame(df2, crs=CRS_METRIC)
 
         assert_frame_equal(traj_gdf, expected_line_gdf)
+
+    def test_to_mf_json(self):
+        json = self.collection.to_mf_json()
+        assert (
+            str(json)
+            == """{'type': 'FeatureCollection', 'features': [{'type': 'Feature', 'properties': {'id': 1, 'obj': 'A', 'val': 9, 'val2': 'a'}, 'temporalGeometry': {'type': 'MovingPoint', 'coordinates': [(0.0, 0.0), (6.0, 0.0), (6.0, 6.0), (9.0, 9.0)], 'datetimes': [Timestamp('2018-01-01 12:00:00'), Timestamp('2018-01-01 12:06:00'), Timestamp('2018-01-01 14:10:00'), Timestamp('2018-01-01 14:15:00')]}}, {'type': 'Feature', 'properties': {'id': 2, 'obj': 'A', 'val': 10, 'val2': 'e'}, 'temporalGeometry': {'type': 'MovingPoint', 'coordinates': [(10.0, 10.0), (16.0, 10.0), (16.0, 16.0), (190.0, 10.0)], 'datetimes': [Timestamp('2018-01-01 12:00:00'), Timestamp('2018-01-01 12:06:00'), Timestamp('2018-01-02 13:10:00'), Timestamp('2018-01-02 13:15:00')]}}]}"""  # noqa F401
+        )

movingpandas/trajectory.py

@@ -33,6 +33,7 @@
 )
 from .spatiotemporal_utils import get_speed2
 from .trajectory_plotter import _TrajectoryPlotter
+from .io import gdf_to_mf_json
 
 warnings.filterwarnings(  # see https://github.com/movingpandas/movingpandas/issues/289
     "ignore", message="CRS not set for some of the concatenation inputs."
@@ -642,6 +643,24 @@ def to_traj_gdf(self, wkt=False, agg=False):
         traj_gdf = GeoDataFrame(df, crs=self.crs)
         return traj_gdf
 
+    def to_mf_json(self):
+        """
+        Converts a Trajectory to a dictionary compatible with the Moving
+        Features JSON (MF-JSON) specification.
+
+        Examples
+        --------
+
+        >>> traj.to_mf_json()
+
+        Returns:
+            dict: The MF-JSON representation of the GeoDataFrame as a dictionary.
+        """
+        tmp = self.to_point_gdf()
+        t = tmp.index.name
+        mf_json = gdf_to_mf_json(tmp.reset_index(), self.get_traj_id_col(), t)
+        return mf_json
+
     def get_start_location(self):
         """
         Return the trajectory's start location.

movingpandas/trajectory_collection.py

@@ -14,6 +14,7 @@
 )
 from .trajectory_plotter import _TrajectoryPlotter
 from .unit_utils import UNITS
+from .io import gdf_to_mf_json
 
 
 @staticmethod
@@ -179,6 +180,24 @@ def to_traj_gdf(self, wkt=False, agg=False):
         gdf.reset_index(drop=True, inplace=True)
         return gdf
 
+    def to_mf_json(self):
+        """
+        Converts a TrajectoryCollection to a dictionary compatible with the Moving
+        Features JSON (MF-JSON) specification.
+
+        Examples
+        --------
+
+        >>> tc.to_mf_json()
+
+        Returns:
+            dict: The MF-JSON representation of the GeoDataFrame as a dictionary.
+        """
+        tmp = self.to_point_gdf()
+        t = tmp.index.name
+        mf_json = gdf_to_mf_json(tmp.reset_index(), self.get_traj_id_col(), t)
+        return mf_json
+
     def _df_to_trajectories(self, df, traj_id_col, obj_id_col, t, x, y, crs):
         trajectories = []
         for traj_id, values in df.groupby(traj_id_col):

tutorials/2-reading-data-from-files.ipynb

@@ -227,7 +227,7 @@
    "id": "eeeadeb1-0f5c-4037-98e0-4f61fda45573",
    "metadata": {},
    "source": [
-    "## Reading MovingFeatures JSONs"
+    "## Reading MovingFeatures JSONs (MF-JSON)"
    ]
   },
   {
@@ -269,9 +269,7 @@
    "id": "peaceful-nomination",
    "metadata": {},
    "source": [
-    "## Writing\n",
-    "\n",
-    "### as points"
+    "## Writing as points"
    ]
   },
   {
@@ -302,7 +300,7 @@
    "id": "animated-worcester",
    "metadata": {},
    "source": [
-    "### as lines"
+    "## Writing as lines"
    ]
   },
   {
@@ -333,7 +331,7 @@
    "id": "french-director",
    "metadata": {},
    "source": [
-    "### as trajectories"
+    "## Writing as trajectories"
    ]
   },
   {
@@ -358,6 +356,35 @@
     "read_file('temp.gpkg', layer='trajectories').plot()"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "990919e0",
+   "metadata": {},
+   "source": [
+    "## Writing as MF-JSON"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "14852dcd",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "mf_json = traj_collection.to_mf_json()\n",
+    "mf_json"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "fd1d069f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "mpd.read_mf_dict(mf_json, traj_id_property ='trajectory_id').plot()"
+   ]
+  },
   {
    "attachments": {},
    "cell_type": "markdown",