Merge remote-tracking branch 'upstream/master' into expr/notimplemented

Author: Zeroto521

CHANGELOG.md

@@ -9,6 +9,7 @@
 - Used `getIndex()` instead of `ptr()` for sorting nonlinear expression terms to avoid nondeterministic behavior 
 ### Changed
 - Return NotImplemented for `Expr` and `GenExpr` operators, if they can't handle input types in the calculation
+- Speed up `constant * Expr` via C-level API
 ### Removed
 - Removed outdated warning about Make build system incompatibility
 

src/pyscipopt/expr.pxi

@@ -248,10 +248,6 @@ cdef class Expr:
         if not isinstance(other, EXPR_OP_TYPES):
             return NotImplemented
 
-        if _is_number(other):
-            f = float(other)
-            return Expr({v: f * c for v, c in self.terms.items()})
-
         cdef dict res = {}
         cdef Py_ssize_t pos1 = <Py_ssize_t>0, pos2 = <Py_ssize_t>0
         cdef PyObject *k1_ptr = NULL
@@ -260,25 +256,31 @@ cdef class Expr:
         cdef PyObject *v2_ptr = NULL
         cdef PyObject *old_v_ptr = NULL
         cdef Term child
-        cdef double prod_v
-
-        while PyDict_Next(self.terms, &pos1, &k1_ptr, &v1_ptr):
-            pos2 = <Py_ssize_t>0
-            while PyDict_Next(other.terms, &pos2, &k2_ptr, &v2_ptr):
-                child = (<Term>k1_ptr) * (<Term>k2_ptr)
-                prod_v = (<double>(<object>v1_ptr)) * (<double>(<object>v2_ptr))
-                if (old_v_ptr := PyDict_GetItem(res, child)) != NULL:
-                    res[child] = <double>(<object>old_v_ptr) + prod_v
-                else:
-                    res[child] = prod_v
+        cdef double coef
+
+        if _is_number(other):
+            coef = <double>other
+            while PyDict_Next(self.terms, &pos1, &k1_ptr, &v1_ptr):
+                res[<Term>k1_ptr] = <double>(<object>v1_ptr) * coef
+
+        elif isinstance(other, Expr):
+            while PyDict_Next(self.terms, &pos1, &k1_ptr, &v1_ptr):
+                pos2 = <Py_ssize_t>0
+                while PyDict_Next(other.terms, &pos2, &k2_ptr, &v2_ptr):
+                    child = (<Term>k1_ptr) * (<Term>k2_ptr)
+                    coef = (<double>(<object>v1_ptr)) * (<double>(<object>v2_ptr))
+                    if (old_v_ptr := PyDict_GetItem(res, child)) != NULL:
+                        res[child] = <double>(<object>old_v_ptr) + coef
+                    else:
+                        res[child] = coef
         return Expr(res)
 
     def __truediv__(self, other):
         if not isinstance(other, EXPR_OP_TYPES):
             return NotImplemented
 
         if _is_number(other):
-            return 1.0 / other * self
+            return 1.0 / <double>other * self
         return buildGenExprObj(self) / other
 
     def __rtruediv__(self, other):

tests/test_expr.py

@@ -224,6 +224,11 @@ def test_mul():
     x = m.addVar(name="x")
     y = m.addVar(name="y")
 
+    # test Expr * number
+    assert str((x + y) * 2.0) == "Expr({Term(x): 2.0, Term(y): 2.0})"
+    assert str(2.0 * (x + y)) == "Expr({Term(x): 2.0, Term(y): 2.0})"
+
+    # test Expr * Expr
     assert str(Expr({CONST: 1.0}) * x) == "Expr({Term(x): 1.0})"
     assert str(y * Expr({CONST: -1.0})) == "Expr({Term(y): -1.0})"
     assert str((x - x) * y) == "Expr({Term(x, y): 0.0})"