xarray.DataTree.std (original) (raw)

DataTree.std(dim=None, *, skipna=None, ddof=0, keep_attrs=None, **kwargs)[source]#

Reduce this DataTree’s data by applying std along some dimension(s).

Parameters:

• dim (str, Iterable of Hashable, "..." or None, default: None) – Name of dimension[s] along which to apply std. For e.g. dim="x"or dim=["x", "y"]. If “…” or None, will reduce over all dimensions.
• skipna (bool or None, optional) – If True, skip missing values (as marked by NaN). By default, only skips missing values for float dtypes; other dtypes either do not have a sentinel missing value (int) or skipna=True has not been implemented (object, datetime64 or timedelta64).
• ddof (int, default: 0) – “Delta Degrees of Freedom”: the divisor used in the calculation is N - ddof, where N represents the number of elements.
• keep_attrs (bool or None, optional) – If True, attrs will be copied from the original object to the new one. If False, the new object will be returned without attributes.
• **kwargs (Any) – Additional keyword arguments passed on to the appropriate array function for calculating std on this object’s data. These could include dask-specific kwargs like split_every.

Returns:

reduced (DataTree) – New DataTree with std applied to its data and the indicated dimension(s) removed

Notes

Non-numeric variables will be removed prior to reducing.

Examples

dt = xr.DataTree( ... xr.Dataset( ... data_vars=dict(foo=("time", np.array([1, 2, 3, 0, 2, np.nan]))), ... coords=dict( ... time=( ... "time", ... pd.date_range("2001-01-01", freq="ME", periods=6), ... ), ... labels=("time", np.array(["a", "b", "c", "c", "b", "a"])), ... ), ... ), ... ) dt <xarray.DataTree> Group: / Dimensions: (time: 6) Coordinates: * time (time) datetime64[ns] 48B 2001-01-31 2001-02-28 ... 2001-06-30 labels (time) <U1 24B 'a' 'b' 'c' 'c' 'b' 'a' Data variables: foo (time) float64 48B 1.0 2.0 3.0 0.0 2.0 nan

dt.std() <xarray.DataTree> Group: / Dimensions: () Data variables: foo float64 8B 1.02

Use skipna to control whether NaNs are ignored.

dt.std(skipna=False) <xarray.DataTree> Group: / Dimensions: () Data variables: foo float64 8B nan

Specify ddof=1 for an unbiased estimate.

dt.std(skipna=True, ddof=1) <xarray.DataTree> Group: / Dimensions: () Data variables: foo float64 8B 1.14