Method ffill

xarray/core/dataarray.py:3685–3767

Fill NaN values by propagating values forward *Requires bottleneck.* Parameters ---------- dim : Hashable Specifies the dimension along which to propagate values when filling. limit : int or None, default: None The maximum

(self, dim: Hashable, limit: int | None = None)

        )

    def ffill(self, dim: Hashable, limit: int | None = None) -> Self:
        """Fill NaN values by propagating values forward

        *Requires bottleneck.*

        Parameters
        ----------
        dim : Hashable
            Specifies the dimension along which to propagate values when
            filling.
        limit : int or None, default: None
            The maximum number of consecutive NaN values to forward fill. In
            other words, if there is a gap with more than this number of
            consecutive NaNs, it will only be partially filled. Must be greater
            than 0 or None for no limit. Must be None or greater than or equal
            to axis length if filling along chunked axes (dimensions).

        Returns
        -------
        filled : DataArray

        Examples
        --------
        >>> temperature = np.array(
        ...     [
        ...         [np.nan, 1, 3],
        ...         [0, np.nan, 5],
        ...         [5, np.nan, np.nan],
        ...         [3, np.nan, np.nan],
        ...         [0, 2, 0],
        ...     ]
        ... )
        >>> da = xr.DataArray(
        ...     data=temperature,
        ...     dims=["Y", "X"],
        ...     coords=dict(
        ...         lat=("Y", np.array([-20.0, -20.25, -20.50, -20.75, -21.0])),
        ...         lon=("X", np.array([10.0, 10.25, 10.5])),
        ...     ),
        ... )
        >>> da
        <xarray.DataArray (Y: 5, X: 3)> Size: 120B
        array([[nan,  1.,  3.],
               [ 0., nan,  5.],
               [ 5., nan, nan],
               [ 3., nan, nan],
               [ 0.,  2.,  0.]])
        Coordinates:
            lat      (Y) float64 40B -20.0 -20.25 -20.5 -20.75 -21.0
            lon      (X) float64 24B 10.0 10.25 10.5
        Dimensions without coordinates: Y, X

        Fill all NaN values:

        >>> da.ffill(dim="Y", limit=None)
        <xarray.DataArray (Y: 5, X: 3)> Size: 120B
        array([[nan,  1.,  3.],
               [ 0.,  1.,  5.],