Merge branch 'vector-assignments' into 'master'

Allow vector assignments

Closes #17

See merge request !133

pystencils/assignment.py

-# -*- coding: utf-8 -*-
 import numpy as np
 import sympy as sp
 from sympy.printing.latex import LatexPrinter
@@ -24,9 +23,20 @@ def assignment_str(assignment):
 
 if Assignment:
 
+    _old_new = sp.codegen.ast.Assignment.__new__
+
+    def _Assignment__new__(cls, lhs, rhs, *args, **kwargs):
+        if isinstance(lhs, (list, tuple, sp.Matrix)) and isinstance(rhs, (list, tuple, sp.Matrix)):
+            assert len(lhs) == len(rhs), f'{lhs} and {rhs} must have same length when performing vector assignment!'
+            return tuple(_old_new(cls, a, b, *args, **kwargs) for a, b in zip(lhs, rhs))
+        return _old_new(cls, lhs, rhs, *args, **kwargs)
+
     Assignment.__str__ = assignment_str
+    Assignment.__new__ = _Assignment__new__
     LatexPrinter._print_Assignment = print_assignment_latex
 
+    sp.MutableDenseMatrix.__hash__ = lambda self: hash(tuple(self))
+
 else:
     # back port for older sympy versions that don't have Assignment  yet
 

pystencils/simp/assignment_collection.py

+import itertools
 from copy import copy
 from typing import Any, Dict, Iterable, Iterator, List, Optional, Sequence, Set, Union
 
@@ -43,6 +44,11 @@ class AssignmentCollection:
             subexpressions = [Assignment(k, v)
                               for k, v in subexpressions.items()]
 
+        main_assignments = list(itertools.chain.from_iterable(
+            [(a if isinstance(a, Iterable) else [a]) for a in main_assignments]))
+        subexpressions = list(itertools.chain.from_iterable(
+            [(a if isinstance(a, Iterable) else [a]) for a in subexpressions]))
+
         self.main_assignments = main_assignments
         self.subexpressions = subexpressions
 

pystencils_tests/test_assignment_collection.py

+import pytest
 import sympy as sp
 
 from pystencils import Assignment, AssignmentCollection
@@ -40,3 +41,39 @@ def test_free_and_defined_symbols():
 
     print(ac)
     print(ac.__repr__)
+
+
+def test_vector_assignments():
+    """From #17 (https://i10git.cs.fau.de/pycodegen/pystencils/issues/17)"""
+
+    import pystencils as ps
+    import sympy as sp
+    a, b, c = sp.symbols("a b c")
+    assignments = ps.Assignment(sp.Matrix([a,b,c]), sp.Matrix([1,2,3]))
+    print(assignments)
+
+
+def test_wrong_vector_assignments():
+    """From #17 (https://i10git.cs.fau.de/pycodegen/pystencils/issues/17)"""
+
+    import pystencils as ps
+    import sympy as sp
+    a, b = sp.symbols("a b")
+    
+    with pytest.raises(AssertionError,
+            match=r'Matrix(.*) and Matrix(.*) must have same length when performing vector assignment!'):
+        ps.Assignment(sp.Matrix([a,b]), sp.Matrix([1,2,3]))
+
+
+def test_vector_assignment_collection():
+    """From #17 (https://i10git.cs.fau.de/pycodegen/pystencils/issues/17)"""
+
+    import pystencils as ps
+    import sympy as sp
+    a, b, c = sp.symbols("a b c")
+    y, x = sp.Matrix([a,b,c]), sp.Matrix([1,2,3])
+    assignments = ps.AssignmentCollection({y: x})
+    print(assignments)
+
+    assignments = ps.AssignmentCollection([ps.Assignment(y,x)])
+    print(assignments)