some new features

.venv/lib/python3.12/site-packages/scipy/sparse/_spfuncs.py

@@ -0,0 +1,76 @@
+""" Functions that operate on sparse matrices
+"""
+
+__all__ = ['count_blocks','estimate_blocksize']
+
+from ._base import issparse
+from ._csr import csr_array
+from ._sparsetools import csr_count_blocks
+
+
+def estimate_blocksize(A,efficiency=0.7):
+    """Attempt to determine the blocksize of a sparse matrix
+
+    Returns a blocksize=(r,c) such that
+        - A.nnz / A.tobsr( (r,c) ).nnz > efficiency
+    """
+    if not (issparse(A) and A.format in ("csc", "csr")):
+        A = csr_array(A)
+
+    if A.nnz == 0:
+        return (1,1)
+
+    if not 0 < efficiency < 1.0:
+        raise ValueError('efficiency must satisfy 0.0 < efficiency < 1.0')
+
+    high_efficiency = (1.0 + efficiency) / 2.0
+    nnz = float(A.nnz)
+    M,N = A.shape
+
+    if M % 2 == 0 and N % 2 == 0:
+        e22 = nnz / (4 * count_blocks(A,(2,2)))
+    else:
+        e22 = 0.0
+
+    if M % 3 == 0 and N % 3 == 0:
+        e33 = nnz / (9 * count_blocks(A,(3,3)))
+    else:
+        e33 = 0.0
+
+    if e22 > high_efficiency and e33 > high_efficiency:
+        e66 = nnz / (36 * count_blocks(A,(6,6)))
+        if e66 > efficiency:
+            return (6,6)
+        else:
+            return (3,3)
+    else:
+        if M % 4 == 0 and N % 4 == 0:
+            e44 = nnz / (16 * count_blocks(A,(4,4)))
+        else:
+            e44 = 0.0
+
+        if e44 > efficiency:
+            return (4,4)
+        elif e33 > efficiency:
+            return (3,3)
+        elif e22 > efficiency:
+            return (2,2)
+        else:
+            return (1,1)
+
+
+def count_blocks(A,blocksize):
+    """For a given blocksize=(r,c) count the number of occupied
+    blocks in a sparse matrix A
+    """
+    r,c = blocksize
+    if r < 1 or c < 1:
+        raise ValueError('r and c must be positive')
+
+    if issparse(A):
+        if A.format == "csr":
+            M,N = A.shape
+            return csr_count_blocks(M,N,r,c,A.indptr,A.indices)
+        elif A.format == "csc":
+            return count_blocks(A.T,(c,r))
+    return count_blocks(csr_array(A),blocksize)