median_abs_deviation

xarray_einstats.stats.median_abs_deviation(da, dims=None, *, center=None, scale=1, nan_policy=None, **kwargs)[source]

Wrap and extend scipy.stats.median_abs_deviation.

Usage examples available at Intro to the stats module.

All parameters take the same values and types as the scipy counterpart with the exception of scale. Here scale can also take DataArray values in which case, broadcasting is handled by xarray, as shown in the example.

Examples

Use a DataArray as scale.

import xarray as xr
from xarray_einstats import tutorial, stats
ds = tutorial.generate_mcmc_like_dataset(3)
s_da = xr.DataArray([1, 2, 1, 1], coords={"chain": ds.chain})
stats.median_abs_deviation(ds["mu"], dims="draw", scale=s_da)
<xarray.DataArray (chain: 4, team: 6)> Size: 192B
0.3468 0.4532 0.5054 0.876 0.6265 0.7342 ... 0.4382 0.5668 0.7103 0.2494 0.3485
Coordinates:
  * team     (team) <U1 24B 'a' 'b' 'c' 'd' 'e' 'f'
  * chain    (chain) int64 32B 0 1 2 3

Note that this doesn’t work with the scipy counterpart because s_da can’t be broadcasted with the output:

from scipy import stats
stats.median_abs_deviation(ds["mu"], axis=1, scale=s_da)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[2], line 2
      1 from scipy import stats
----> 2 stats.median_abs_deviation(ds["mu"], axis=1, scale=s_da)

File ~/checkouts/readthedocs.org/user_builds/xarray-einstats/envs/stable/lib/python3.10/site-packages/scipy/stats/_stats_py.py:3617, in median_abs_deviation(x, axis, center, scale, nan_policy)
   3614         med = np.expand_dims(center(x, axis=axis), axis)
   3615         mad = np.median(np.abs(x - med), axis=axis)
-> 3617 return mad / scale

File ~/checkouts/readthedocs.org/user_builds/xarray-einstats/envs/stable/lib/python3.10/site-packages/xarray/core/arithmetic.py:83, in SupportsArithmetic.__array_ufunc__(self, ufunc, method, *inputs, **kwargs)
     74     raise NotImplementedError(
     75         "xarray objects are not yet supported in the `out` argument "
     76         "for ufuncs. As an alternative, consider explicitly "
     77         "converting xarray objects to NumPy arrays (e.g., with "
     78         "`.values`)."
     79     )
     81 join = dataset_join = OPTIONS["arithmetic_join"]
---> 83 return apply_ufunc(
     84     ufunc,
     85     *inputs,
     86     input_core_dims=((),) * ufunc.nin,
     87     output_core_dims=((),) * ufunc.nout,
     88     join=join,
     89     dataset_join=dataset_join,
     90     dataset_fill_value=np.nan,
     91     kwargs=kwargs,
     92     dask="allowed",
     93     keep_attrs=_get_keep_attrs(default=True),
     94 )

File ~/checkouts/readthedocs.org/user_builds/xarray-einstats/envs/stable/lib/python3.10/site-packages/xarray/core/computation.py:1278, in apply_ufunc(func, input_core_dims, output_core_dims, exclude_dims, vectorize, join, dataset_join, dataset_fill_value, keep_attrs, kwargs, dask, output_dtypes, output_sizes, meta, dask_gufunc_kwargs, on_missing_core_dim, *args)
   1276 # feed DataArray apply_variable_ufunc through apply_dataarray_vfunc
   1277 elif any(isinstance(a, DataArray) for a in args):
-> 1278     return apply_dataarray_vfunc(
   1279         variables_vfunc,
   1280         *args,
   1281         signature=signature,
   1282         join=join,
   1283         exclude_dims=exclude_dims,
   1284         keep_attrs=keep_attrs,
   1285     )
   1286 # feed Variables directly through apply_variable_ufunc
   1287 elif any(isinstance(a, Variable) for a in args):

File ~/checkouts/readthedocs.org/user_builds/xarray-einstats/envs/stable/lib/python3.10/site-packages/xarray/core/computation.py:320, in apply_dataarray_vfunc(func, signature, join, exclude_dims, keep_attrs, *args)
    315 result_coords, result_indexes = build_output_coords_and_indexes(
    316     args, signature, exclude_dims, combine_attrs=keep_attrs
    317 )
    319 data_vars = [getattr(a, "variable", a) for a in args]
--> 320 result_var = func(*data_vars)
    322 out: tuple[DataArray, ...] | DataArray
    323 if signature.num_outputs > 1:

File ~/checkouts/readthedocs.org/user_builds/xarray-einstats/envs/stable/lib/python3.10/site-packages/xarray/core/computation.py:831, in apply_variable_ufunc(func, signature, exclude_dims, dask, output_dtypes, vectorize, keep_attrs, dask_gufunc_kwargs, *args)
    826     if vectorize:
    827         func = _vectorize(
    828             func, signature, output_dtypes=output_dtypes, exclude_dims=exclude_dims
    829         )
--> 831 result_data = func(*input_data)
    833 if signature.num_outputs == 1:
    834     result_data = (result_data,)

ValueError: operands could not be broadcast together with shapes (4,6) (4,)