467 lines
14 KiB
Python
467 lines
14 KiB
Python
from collections.abc import Callable
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from sympy.core.compatibility import as_int, is_sequence
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from sympy.core.containers import Dict
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from sympy.utilities.exceptions import SymPyDeprecationWarning
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from .matrices import MatrixBase
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from .repmatrix import MutableRepMatrix, RepMatrix
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from .utilities import _iszero
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from .decompositions import (
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_liupc, _row_structure_symbolic_cholesky, _cholesky_sparse,
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_LDLdecomposition_sparse)
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from .solvers import (
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_lower_triangular_solve_sparse, _upper_triangular_solve_sparse)
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class SparseMatrix(RepMatrix):
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"""
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A sparse matrix (a matrix with a large number of zero elements).
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Examples
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========
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>>> from sympy.matrices import SparseMatrix, ones
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>>> SparseMatrix(2, 2, range(4))
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Matrix([
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[0, 1],
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[2, 3]])
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>>> SparseMatrix(2, 2, {(1, 1): 2})
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Matrix([
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[0, 0],
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[0, 2]])
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A SparseMatrix can be instantiated from a ragged list of lists:
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>>> SparseMatrix([[1, 2, 3], [1, 2], [1]])
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Matrix([
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[1, 2, 3],
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[1, 2, 0],
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[1, 0, 0]])
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For safety, one may include the expected size and then an error
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will be raised if the indices of any element are out of range or
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(for a flat list) if the total number of elements does not match
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the expected shape:
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>>> SparseMatrix(2, 2, [1, 2])
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Traceback (most recent call last):
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...
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ValueError: List length (2) != rows*columns (4)
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Here, an error is not raised because the list is not flat and no
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element is out of range:
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>>> SparseMatrix(2, 2, [[1, 2]])
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Matrix([
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[1, 2],
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[0, 0]])
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But adding another element to the first (and only) row will cause
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an error to be raised:
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>>> SparseMatrix(2, 2, [[1, 2, 3]])
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Traceback (most recent call last):
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...
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ValueError: The location (0, 2) is out of designated range: (1, 1)
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To autosize the matrix, pass None for rows:
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>>> SparseMatrix(None, [[1, 2, 3]])
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Matrix([[1, 2, 3]])
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>>> SparseMatrix(None, {(1, 1): 1, (3, 3): 3})
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Matrix([
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[0, 0, 0, 0],
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[0, 1, 0, 0],
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[0, 0, 0, 0],
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[0, 0, 0, 3]])
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Values that are themselves a Matrix are automatically expanded:
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>>> SparseMatrix(4, 4, {(1, 1): ones(2)})
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Matrix([
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[0, 0, 0, 0],
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[0, 1, 1, 0],
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[0, 1, 1, 0],
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[0, 0, 0, 0]])
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A ValueError is raised if the expanding matrix tries to overwrite
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a different element already present:
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>>> SparseMatrix(3, 3, {(0, 0): ones(2), (1, 1): 2})
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Traceback (most recent call last):
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...
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ValueError: collision at (1, 1)
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See Also
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========
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DenseMatrix
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MutableSparseMatrix
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ImmutableSparseMatrix
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"""
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@classmethod
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def _handle_creation_inputs(cls, *args, **kwargs):
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if len(args) == 1 and isinstance(args[0], MatrixBase):
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rows = args[0].rows
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cols = args[0].cols
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smat = args[0].todok()
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return rows, cols, smat
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smat = {}
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# autosizing
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if len(args) == 2 and args[0] is None:
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args = [None, None, args[1]]
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if len(args) == 3:
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r, c = args[:2]
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if r is c is None:
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rows = cols = None
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elif None in (r, c):
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raise ValueError(
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'Pass rows=None and no cols for autosizing.')
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else:
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rows, cols = as_int(args[0]), as_int(args[1])
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if isinstance(args[2], Callable):
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op = args[2]
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if None in (rows, cols):
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raise ValueError(
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"{} and {} must be integers for this "
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"specification.".format(rows, cols))
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row_indices = [cls._sympify(i) for i in range(rows)]
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col_indices = [cls._sympify(j) for j in range(cols)]
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for i in row_indices:
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for j in col_indices:
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value = cls._sympify(op(i, j))
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if value != cls.zero:
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smat[i, j] = value
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return rows, cols, smat
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elif isinstance(args[2], (dict, Dict)):
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def update(i, j, v):
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# update smat and make sure there are no collisions
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if v:
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if (i, j) in smat and v != smat[i, j]:
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raise ValueError(
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"There is a collision at {} for {} and {}."
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.format((i, j), v, smat[i, j])
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)
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smat[i, j] = v
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# manual copy, copy.deepcopy() doesn't work
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for (r, c), v in args[2].items():
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if isinstance(v, MatrixBase):
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for (i, j), vv in v.todok().items():
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update(r + i, c + j, vv)
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elif isinstance(v, (list, tuple)):
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_, _, smat = cls._handle_creation_inputs(v, **kwargs)
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for i, j in smat:
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update(r + i, c + j, smat[i, j])
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else:
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v = cls._sympify(v)
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update(r, c, cls._sympify(v))
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elif is_sequence(args[2]):
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flat = not any(is_sequence(i) for i in args[2])
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if not flat:
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_, _, smat = \
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cls._handle_creation_inputs(args[2], **kwargs)
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else:
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flat_list = args[2]
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if len(flat_list) != rows * cols:
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raise ValueError(
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"The length of the flat list ({}) does not "
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"match the specified size ({} * {})."
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.format(len(flat_list), rows, cols)
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)
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for i in range(rows):
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for j in range(cols):
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value = flat_list[i*cols + j]
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value = cls._sympify(value)
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if value != cls.zero:
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smat[i, j] = value
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if rows is None: # autosizing
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keys = smat.keys()
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rows = max([r for r, _ in keys]) + 1 if keys else 0
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cols = max([c for _, c in keys]) + 1 if keys else 0
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else:
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for i, j in smat.keys():
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if i and i >= rows or j and j >= cols:
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raise ValueError(
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"The location {} is out of the designated range"
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"[{}, {}]x[{}, {}]"
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.format((i, j), 0, rows - 1, 0, cols - 1)
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)
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return rows, cols, smat
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elif len(args) == 1 and isinstance(args[0], (list, tuple)):
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# list of values or lists
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v = args[0]
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c = 0
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for i, row in enumerate(v):
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if not isinstance(row, (list, tuple)):
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row = [row]
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for j, vv in enumerate(row):
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if vv != cls.zero:
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smat[i, j] = cls._sympify(vv)
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c = max(c, len(row))
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rows = len(v) if c else 0
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cols = c
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return rows, cols, smat
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else:
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# handle full matrix forms with _handle_creation_inputs
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rows, cols, mat = super()._handle_creation_inputs(*args)
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for i in range(rows):
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for j in range(cols):
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value = mat[cols*i + j]
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if value != cls.zero:
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smat[i, j] = value
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return rows, cols, smat
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@property
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def _smat(self):
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SymPyDeprecationWarning(
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feature="The private _smat attribute of SparseMatrix",
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useinstead="the .todok() method",
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issue=21715,
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deprecated_since_version="1.9").warn()
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return self.todok()
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def _eval_inverse(self, **kwargs):
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return self.inv(method=kwargs.get('method', 'LDL'),
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iszerofunc=kwargs.get('iszerofunc', _iszero),
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try_block_diag=kwargs.get('try_block_diag', False))
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def applyfunc(self, f):
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"""Apply a function to each element of the matrix.
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Examples
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========
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>>> from sympy.matrices import SparseMatrix
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>>> m = SparseMatrix(2, 2, lambda i, j: i*2+j)
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>>> m
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Matrix([
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[0, 1],
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[2, 3]])
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>>> m.applyfunc(lambda i: 2*i)
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Matrix([
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[0, 2],
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[4, 6]])
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"""
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if not callable(f):
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raise TypeError("`f` must be callable.")
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# XXX: This only applies the function to the nonzero elements of the
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# matrix so is inconsistent with DenseMatrix.applyfunc e.g.
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# zeros(2, 2).applyfunc(lambda x: x + 1)
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dok = {}
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for k, v in self.todok().items():
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fv = f(v)
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if fv != 0:
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dok[k] = fv
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return self._new(self.rows, self.cols, dok)
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def as_immutable(self):
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"""Returns an Immutable version of this Matrix."""
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from .immutable import ImmutableSparseMatrix
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return ImmutableSparseMatrix(self)
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def as_mutable(self):
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"""Returns a mutable version of this matrix.
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Examples
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========
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>>> from sympy import ImmutableMatrix
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>>> X = ImmutableMatrix([[1, 2], [3, 4]])
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>>> Y = X.as_mutable()
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>>> Y[1, 1] = 5 # Can set values in Y
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>>> Y
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Matrix([
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[1, 2],
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[3, 5]])
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"""
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return MutableSparseMatrix(self)
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def col_list(self):
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"""Returns a column-sorted list of non-zero elements of the matrix.
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Examples
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========
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>>> from sympy.matrices import SparseMatrix
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>>> a=SparseMatrix(((1, 2), (3, 4)))
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>>> a
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Matrix([
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[1, 2],
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[3, 4]])
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>>> a.CL
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[(0, 0, 1), (1, 0, 3), (0, 1, 2), (1, 1, 4)]
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See Also
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========
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sympy.matrices.sparse.SparseMatrix.row_list
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"""
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return [tuple(k + (self[k],)) for k in sorted(list(self.todok().keys()), key=lambda k: list(reversed(k)))]
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def nnz(self):
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"""Returns the number of non-zero elements in Matrix."""
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return len(self.todok())
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def row_list(self):
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"""Returns a row-sorted list of non-zero elements of the matrix.
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Examples
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========
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>>> from sympy.matrices import SparseMatrix
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>>> a = SparseMatrix(((1, 2), (3, 4)))
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>>> a
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Matrix([
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[1, 2],
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[3, 4]])
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>>> a.RL
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[(0, 0, 1), (0, 1, 2), (1, 0, 3), (1, 1, 4)]
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See Also
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========
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sympy.matrices.sparse.SparseMatrix.col_list
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"""
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return [tuple(k + (self[k],)) for k in
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sorted(self.todok().keys(), key=lambda k: list(k))]
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def scalar_multiply(self, scalar):
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"Scalar element-wise multiplication"
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return scalar * self
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def solve_least_squares(self, rhs, method='LDL'):
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"""Return the least-square fit to the data.
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By default the cholesky_solve routine is used (method='CH'); other
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methods of matrix inversion can be used. To find out which are
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available, see the docstring of the .inv() method.
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Examples
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========
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>>> from sympy.matrices import SparseMatrix, Matrix, ones
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>>> A = Matrix([1, 2, 3])
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>>> B = Matrix([2, 3, 4])
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>>> S = SparseMatrix(A.row_join(B))
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>>> S
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Matrix([
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[1, 2],
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[2, 3],
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[3, 4]])
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If each line of S represent coefficients of Ax + By
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and x and y are [2, 3] then S*xy is:
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>>> r = S*Matrix([2, 3]); r
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Matrix([
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[ 8],
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[13],
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[18]])
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But let's add 1 to the middle value and then solve for the
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least-squares value of xy:
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>>> xy = S.solve_least_squares(Matrix([8, 14, 18])); xy
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Matrix([
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[ 5/3],
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[10/3]])
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The error is given by S*xy - r:
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>>> S*xy - r
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Matrix([
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[1/3],
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[1/3],
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[1/3]])
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>>> _.norm().n(2)
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0.58
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If a different xy is used, the norm will be higher:
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>>> xy += ones(2, 1)/10
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>>> (S*xy - r).norm().n(2)
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1.5
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"""
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t = self.T
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return (t*self).inv(method=method)*t*rhs
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def solve(self, rhs, method='LDL'):
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"""Return solution to self*soln = rhs using given inversion method.
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For a list of possible inversion methods, see the .inv() docstring.
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"""
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if not self.is_square:
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if self.rows < self.cols:
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raise ValueError('Under-determined system.')
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elif self.rows > self.cols:
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raise ValueError('For over-determined system, M, having '
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'more rows than columns, try M.solve_least_squares(rhs).')
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else:
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return self.inv(method=method).multiply(rhs)
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RL = property(row_list, None, None, "Alternate faster representation")
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CL = property(col_list, None, None, "Alternate faster representation")
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def liupc(self):
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return _liupc(self)
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def row_structure_symbolic_cholesky(self):
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return _row_structure_symbolic_cholesky(self)
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def cholesky(self, hermitian=True):
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return _cholesky_sparse(self, hermitian=hermitian)
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def LDLdecomposition(self, hermitian=True):
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return _LDLdecomposition_sparse(self, hermitian=hermitian)
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def lower_triangular_solve(self, rhs):
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return _lower_triangular_solve_sparse(self, rhs)
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def upper_triangular_solve(self, rhs):
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return _upper_triangular_solve_sparse(self, rhs)
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liupc.__doc__ = _liupc.__doc__
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row_structure_symbolic_cholesky.__doc__ = _row_structure_symbolic_cholesky.__doc__
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cholesky.__doc__ = _cholesky_sparse.__doc__
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LDLdecomposition.__doc__ = _LDLdecomposition_sparse.__doc__
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lower_triangular_solve.__doc__ = lower_triangular_solve.__doc__
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upper_triangular_solve.__doc__ = upper_triangular_solve.__doc__
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class MutableSparseMatrix(SparseMatrix, MutableRepMatrix):
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@classmethod
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def _new(cls, *args, **kwargs):
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rows, cols, smat = cls._handle_creation_inputs(*args, **kwargs)
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rep = cls._smat_to_DomainMatrix(rows, cols, smat)
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return cls._fromrep(rep)
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