WIP: Enable array api support in neighbor #2700

david-cortes-intel · 2026-01-23T14:31:28Z

If this now runs on GPU, then please add it to the support table in algorithms.rst.

I don't think it does, but this list is not exclusively GPU algorithms

@yuejiaointel @ethanglaser I have it a try and both onedal and sklearnex report that it runs on GPU:

INFO:sklearnex: sklearn.neighbors.LocalOutlierFactor.fit: running accelerated version on GPU

----------------------------------------------------------------------------- File: cpp/oneapi/dal/backend/primitives/search/search_dpc.cpp, Line: 48 Profiler task_name: search.treat_indices, q search.treat_indices 24.89ms search.squared_l2.inner_blocking 249.78ms ----------------------------------------------------------------------------- File: cpp/oneapi/dal/backend/primitives/search/search_dpc.cpp, Line: 608 Profiler task_name: selection_loop.selection, this->get_queue() -----------------------------------------------------------------------------

But some things I'm not clear whether they are CPU or GPU:

----------------------------------------------------------------------------- File: [./cpp/oneapi/dal/backend/primitives/reduction/reduction.hpp](https://vscode-remote+ssh-002dremote-002bsdpdal630226-002ejf-002eintel-002ecom.vscode-resource.vscode-cdn.net/export/users/dcortes/repos/sklex-dpnp/cpp/oneapi/dal/backend/primitives/reduction/reduction.hpp), Line: 60 Profiler task_name: reduction.reduce_by_rows, q reduction.reduce_by_rows 40.87ms ----------------------------------------------------------------------------- File: [./cpp/oneapi/dal/backend/primitives/reduction/reduction.hpp](https://vscode-remote+ssh-002dremote-002bsdpdal630226-002ejf-002eintel-002ecom.vscode-resource.vscode-cdn.net/export/users/dcortes/repos/sklex-dpnp/cpp/oneapi/dal/backend/primitives/reduction/reduction.hpp), Line: 60 Profiler task_name: reduction.reduce_by_rows, q reduction.reduce_by_rows 11.97us -----------------------------------------------------------------------------

@Alexandr-Solovev @Vika-F Could you comment on what's the status of GPU support for LocalOutlierFactor?

We currently don’t have a native LocalOutlierFactor implementation in oneDAL. There is a CPU-only implementation in the legacy DAAL part, but it is not exposed through oneAPI interfaces. As a result, GPU support for LocalOutlierFactor is not available.

For reference:

scikit-learn-intelex/sklearnex/neighbors/_lof.py

Line 86 in bf43701

self._lrd = self._local_reachability_density(

Looks like our LOF impl is a mix of oneDAL knn call + additional python calls on CPU.

It looks like it'd be very easy to port those python parts to array API to run them on GPU, since they only do slicing and max ops.

@Alexandr-Solovev Do I understand it correctly from the logs above that all the operations offloaded to oneDAL are running on GPU?

Example:

import os os.environ["SCIPY_ARRAY_API"] = "1" os.environ["SKLEARNEX_VERBOSE"] = "INFO" os.environ["ONEDAL_VERBOSE"] = "4" import numpy as np import dpnp rng = np.random.default_rng(seed=123) X = rng.standard_normal(size=(1000, 20), dtype=np.float32) Xd = dpnp.array(X, device="gpu") from sklearnex import config_context from sklearnex.neighbors import LocalOutlierFactor with config_context(array_api_dispatch=True): model = LocalOutlierFactor().fit(Xd)

yes, all of the operations offloaded to oneDAL from the kernel_profiler log are executed on GPU

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WIP: Enable array api support in neighbor #2700

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WIP: Enable array api support in neighbor #2700

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