API: Initial finch_backend (#649)

* API: Initial finch backend

Co-authored-by: Hameer Abbasi <[email protected]>

Author: mtsokol

.github/workflows/ci.yml

@@ -34,6 +34,9 @@ jobs:
           key:
             test-${{ matrix.os }}-conda-py${{ matrix.python }}-${{ env.CACHE_NUMBER }}-${{
             hashFiles('ci/environment.yml') }}
+      - uses: julia-actions/setup-julia@v1
+        with:
+          version: '1.10.0'
       - uses: conda-incubator/setup-miniconda@v3
         with:
           activate-environment: sparse-dev

ci/environment.yml

@@ -2,4 +2,5 @@ name: sparse-dev
 channels:
   - conda-forge
 dependencies:
+  - python
   - pip

pyproject.toml

@@ -34,6 +34,7 @@ tests = [
     "pytest-cov",
     "pre-commit",
     "scipy",
+    "sparse[finch]",
 ]
 tox = ["sparse[tests]", "tox"]
 all = ["sparse[docs,tox]", "matrepr"]

sparse/__init__.py

@@ -26,8 +26,7 @@ def __init__(self, backend=BackendType.PyData):
         self.token = None
 
     def __enter__(self):
-        token = backend_var.set(self.backend)
-        self.token = token
+        self.token = backend_var.set(self.backend)
 
     def __exit__(self, exc_type, exc_value, traceback):
         backend_var.reset(self.token)

sparse/finch_backend/__init__.py

@@ -1,4 +1,11 @@
-Tensor = ()
+try:
+    import finch  # noqa: F401
+except ModuleNotFoundError as e:
+    raise ImportError("Finch not installed. Run `pip install sparse[finch]` to enable Finch backend") from e
+
+from finch import Tensor, astype, permute_dims
+
+__all__ = ["Tensor", "astype", "permute_dims"]
 
 
 class COO:

sparse/tests/test_backends.py

@@ -3,6 +3,7 @@
 import pytest
 
 import numpy as np
+import scipy.sparse as sp
 
 
 def test_backend_contex_manager(backend):
@@ -11,3 +12,21 @@ def test_backend_contex_manager(backend):
             sparse.COO.from_numpy(np.eye(5))
     else:
         sparse.COO.from_numpy(np.eye(5))
+
+
+def test_finch_backend():
+    np_eye = np.eye(5)
+    sp_arr = sp.csr_matrix(np_eye)
+
+    with sparse.Backend(backend=sparse.BackendType.Finch):
+        finch_dense = sparse.Tensor(np_eye)
+
+        assert np.shares_memory(finch_dense.todense(), np_eye)
+
+        finch_arr = sparse.Tensor(sp_arr)
+
+        np.testing.assert_equal(finch_arr.todense(), np_eye)
+
+        transposed = sparse.permute_dims(finch_arr, (1, 0))
+
+        np.testing.assert_equal(transposed.todense(), np_eye.T)