# xarray.DataArray.rolling_exp

`DataArray.``rolling_exp`(window: Mapping[Hashable, int] = None, window_type: str = 'span', **window_kwargs)

  Exponentially-weighted moving window. Similar to EWM in pandas

  Requires the optional Numbagg dependency.

  Parameters:

  - window (A single mapping from a dimension name to window value,) –

    optional

    dim : str
      Name of the dimension to create the rolling exponential window along (e.g., time).
    window : int
      Size of the moving window. The type of this is specified in window_type
  - window_type (str, one of ['span', 'com', 'halflife', 'alpha'],) – default ‘span’ The format of the previously supplied window. Each is a simple numerical transformation of the others. Described in detail: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.ewm.html
  - **window_kwargs (optional) – The keyword arguments form of `window`. One of window or window_kwargs must be provided.

  See also

  `core.rolling_exp.RollingExp()`