Source code for ufl.indexed

"""This module defines the Indexed class."""

# Copyright (C) 2008-2016 Martin Sandve Aln├Žs
#
# This file is part of UFL (https://www.fenicsproject.org)
#
# SPDX-License-Identifier:    LGPL-3.0-or-later

from ufl.constantvalue import Zero
from ufl.core.expr import Expr, ufl_err_str
from ufl.core.multiindex import FixedIndex, Index, MultiIndex
from ufl.core.operator import Operator
from ufl.core.ufl_type import ufl_type
from ufl.index_combination_utils import unique_sorted_indices
from ufl.precedence import parstr


[docs]@ufl_type(is_shaping=True, num_ops=2, is_terminal_modifier=True) class Indexed(Operator): """Indexed expression.""" __slots__ = ( "ufl_free_indices", "ufl_index_dimensions", ) def __new__(cls, expression, multiindex): """Create a new Indexed.""" if isinstance(expression, Zero): # Zero-simplify indexed Zero objects shape = expression.ufl_shape efi = expression.ufl_free_indices efid = expression.ufl_index_dimensions fi = list(zip(efi, efid)) for pos, ind in enumerate(multiindex._indices): if isinstance(ind, Index): fi.append((ind.count(), shape[pos])) fi = unique_sorted_indices(sorted(fi)) if fi: fi, fid = zip(*fi) else: fi, fid = (), () return Zero(shape=(), free_indices=fi, index_dimensions=fid) elif expression.ufl_shape == () and multiindex == (): return expression else: return Operator.__new__(cls) def __init__(self, expression, multiindex): """Initialise.""" # Store operands Operator.__init__(self, (expression, multiindex)) # Error checking if not isinstance(expression, Expr): raise ValueError(f"Expecting Expr instance, not {ufl_err_str(expression)}.") if not isinstance(multiindex, MultiIndex): raise ValueError(f"Expecting MultiIndex instance, not {ufl_err_str(multiindex)}.") shape = expression.ufl_shape # Error checking if len(shape) != len(multiindex): raise ValueError( f"Invalid number of indices ({len(multiindex)}) for tensor " f"expression of rank {len(expression.ufl_shape)}:\n {ufl_err_str(expression)}" ) if any( int(di) >= int(si) or int(di) < 0 for si, di in zip(shape, multiindex) if isinstance(di, FixedIndex) ): raise ValueError("Fixed index out of range!") # Build tuples of free index ids and dimensions efi = expression.ufl_free_indices efid = expression.ufl_index_dimensions fi = list(zip(efi, efid)) for pos, ind in enumerate(multiindex._indices): if isinstance(ind, Index): fi.append((ind.count(), shape[pos])) fi = unique_sorted_indices(sorted(fi)) if fi: fi, fid = zip(*fi) else: fi, fid = (), () # Cache free index and dimensions self.ufl_free_indices = fi self.ufl_index_dimensions = fid ufl_shape = ()
[docs] def evaluate(self, x, mapping, component, index_values, derivatives=()): """Evaluate.""" A, ii = self.ufl_operands component = ii.evaluate(x, mapping, None, index_values) if derivatives: return A.evaluate(x, mapping, component, index_values, derivatives) else: return A.evaluate(x, mapping, component, index_values)
def __str__(self): """Format as a string.""" return "%s[%s]" % (parstr(self.ufl_operands[0], self), self.ufl_operands[1]) def __getitem__(self, key): """Get an item.""" if key == (): # So that one doesn't have to special case indexing of # expressions without shape. return self raise ValueError( f"Attempting to index with {ufl_err_str(key)}, " f"but object is already indexed: {ufl_err_str(self)}" )