# xarray.Dataset.combine_first

#### Dataset.combine_first(other)[[source]](https://github.com/pydata/xarray/blob/main/xarray/core/dataset.py#L6885-L6902)

Combine two Datasets, default to data_vars of self.

The new coordinates follow the normal broadcasting and alignment rules
of `join='outer'`.  Vacant cells in the expanded coordinates are
filled with np.nan.

* **Parameters:**
  **other** ([`Dataset`](xarray.Dataset.html.md#xarray.Dataset)) – Used to fill all matching missing values in this array.
* **Returns:**
  [`Dataset`](xarray.Dataset.html.md#xarray.Dataset)