# xarray.computation.rolling_exp.RollingExp.sum

#### RollingExp.sum(keep_attrs=None)[[source]](https://github.com/pydata/xarray/blob/main/xarray/computation/rolling_exp.py#L135-L171)

Exponentially weighted moving sum.

* **Parameters:**
  **keep_attrs** ([`bool`](https://docs.python.org/3/builtins/functions.html#bool), *default*: [`None`](https://docs.python.org/3/builtins/constants.html#None)) – If True, the attributes (`attrs`) will be copied from the original
  object to the new one. If False, the new object will be returned
  without attributes. If None uses the global default.

### Examples

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```pycon
>>> da = xr.DataArray([1, 1, 2, 2, 2], dims="x")
>>> da.rolling_exp(x=2, window_type="span").sum()
<xarray.DataArray (x: 5)> Size: 40B
array([1.        , 1.33333333, 2.44444444, 2.81481481, 2.9382716 ])
Dimensions without coordinates: x
```

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