traj: add gridobs abstract method

Author: gauteh

docs/source/api.rst

@@ -121,6 +121,7 @@ Methods
     Dataset.traj.convex_hull_contains_point
     Dataset.traj.get_area_convex_hull
     Dataset.traj.gridtime
+    Dataset.traj.gridobs
     Dataset.traj.seltime
     Dataset.traj.iseltime
     Dataset.traj.is_1d

trajan/traj.py

@@ -666,6 +666,21 @@ def gridtime(self, times, timedim=None) -> xr.Dataset:
             A new dataset interpolated to the target times. The dataset will be 1D (i.e. gridded) and the time dimension will be named `time`.
         """
 
+    @abstractmethod
+    def gridobs(self, times) -> xr.Dataset:
+        """Interpolate dataset to observation times.
+
+        Parameters
+        ----------
+        times : DataArray (trajectory, obs)
+            A time variable with the target times for each trajectory.
+
+        Returns
+        -------
+        Dataset
+            A new dataset interpolated to the target times. The dataset will be 2D (i.e. observational).
+        """
+
     @abstractmethod
     def seltime(self, t0=None, t1=None) -> xr.Dataset:
         """Select observations in time window between `t0` and `t1` (inclusive). For 1D datasets prefer to use `xarray.Dataset.sel`.