Method assign_coords

xarray/core/common.py:520–665

Assign new coordinates to this object. Returns a new object with all the original data in addition to the new coordinates. Parameters ---------- coords : mapping of dim to coord, optional A mapping whose keys are the names of the coordinates and

(
        self,
        coords: Mapping | None = None,
        **coords_kwargs: Any,
    )

        return {k: v(self) if callable(v) else v for k, v in kwargs.items()}

    def assign_coords(
        self,
        coords: Mapping | None = None,
        **coords_kwargs: Any,
    ) -> Self:
        """Assign new coordinates to this object.

        Returns a new object with all the original data in addition to the new
        coordinates.

        Parameters
        ----------
        coords : mapping of dim to coord, optional
            A mapping whose keys are the names of the coordinates and values are the
            coordinates to assign. The mapping will generally be a dict or
            :class:`Coordinates`.

            * If a value is a standard data value — for example, a ``DataArray``,
              scalar, or array — the data is simply assigned as a coordinate.

            * If a value is callable, it is called with this object as the only
              parameter, and the return value is used as new coordinate variables.

            * A coordinate can also be defined and attached to an existing dimension
              using a tuple with the first element the dimension name and the second
              element the values for this new coordinate.

        **coords_kwargs : optional
            The keyword arguments form of ``coords``.
            One of ``coords`` or ``coords_kwargs`` must be provided.

        Returns
        -------
        assigned : same type as caller
            A new object with the new coordinates in addition to the existing
            data.

        Examples
        --------
        Convert `DataArray` longitude coordinates from 0-359 to -180-179:

        >>> da = xr.DataArray(
        ...     np.random.rand(4),
        ...     coords=[np.array([358, 359, 0, 1])],
        ...     dims="lon",
        ... )
        >>> da
        <xarray.DataArray (lon: 4)> Size: 32B
        array([0.5488135 , 0.71518937, 0.60276338, 0.54488318])
        Coordinates:
          * lon      (lon) int64 32B 358 359 0 1
        >>> da.assign_coords(lon=(((da.lon + 180) % 360) - 180))
        <xarray.DataArray (lon: 4)> Size: 32B
        array([0.5488135 , 0.71518937, 0.60276338, 0.54488318])
        Coordinates:
          * lon      (lon) int64 32B -2 -1 0 1

        The function also accepts dictionary arguments: