Remove .id

CHANGELOG.md

@@ -1,4 +1,10 @@
 # [Unreleased](https://github.com/pybamm-team/PyBaMM/)
+## Features
+
+-   Added `__eq__` and `__hash__` methods for `Symbol` objects, using `.id` ([#1978](https://github.com/pybamm-team/PyBaMM/pull/1978))
+## Breaking changes
+
+-   Changed some dictionary keys to `Symbol` instead of `Symbol.id` (internal change only, should not affect external facing functions) ([#1978](https://github.com/pybamm-team/PyBaMM/pull/1978))
 
 # [v22.5](https://github.com/pybamm-team/PyBaMM/tree/v22.5) - 2022-05-31
 
@@ -32,6 +38,10 @@
 -   Added "Discharge energy [W.h]", which is the integral of the power in Watts, as an optional output. Set the option "calculate discharge energy" to "true" to get this output ("false" by default, since it can slow down some of the simple models) ([#1969](https://github.com/pybamm-team/PyBaMM/pull/1969)))
 -   Added an option "calculate heat source for isothermal models" to choose whether or not the heat generation terms are computed when running models with the option `thermal="isothermal"`  ([#1958](https://github.com/pybamm-team/PyBaMM/pull/1958))
 
+## Optimizations
+
+-   Simplified `model.new_copy()` ([#1977](https://github.com/pybamm-team/PyBaMM/pull/1977))
+
 ## Bug fixes
 
 -   Fix bug where sensitivity calculation failed if len of `calculate_sensitivities` was less than `inputs` ([#1897](https://github.com/pybamm-team/PyBaMM/pull/1897))
@@ -40,6 +50,7 @@
 
 ## Breaking changes
 
+-   Removed `model.new_empty_copy()` (use `model.new_copy()` instead) ([#1977](https://github.com/pybamm-team/PyBaMM/pull/1977))
 -   Dropped support for Windows 32-bit architecture ([#1964](https://github.com/pybamm-team/PyBaMM/pull/1964))
 
 # [v22.2](https://github.com/pybamm-team/PyBaMM/tree/v22.2) - 2022-02-28

examples/notebooks/expression_tree/expression-tree.ipynb

@@ -198,7 +198,7 @@
    "source": [
     "from tests import get_discretisation_for_testing\n",
     "disc = get_discretisation_for_testing()\n",
-    "disc.y_slices = {c.id: [slice(0, 40)]}\n",
+    "disc.y_slices = {c: [slice(0, 40)]}\n",
     "dcdt = disc.process_symbol(dcdt)\n",
     "dcdt.visualise('expression_tree5.png')"
    ]

pybamm/discretisations/discretisation.py

@@ -10,8 +10,8 @@
 
 def has_bc_of_form(symbol, side, bcs, form):
 
-    if symbol.id in bcs:
-        if bcs[symbol.id][side][1] == form:
+    if symbol in bcs:
+        if bcs[symbol][side][1] == form:
             return True
         else:
             return False
@@ -292,15 +292,15 @@ def set_variable_slices(self, variables):
                         for domain_mesh in mesh:
                             end += domain_mesh.npts_for_broadcast_to_nodes
                         # Add to slices
-                        y_slices[child.id].append(slice(start_, end))
+                        y_slices[child].append(slice(start_, end))
                         y_slices_explicit[child].append(slice(start_, end))
                         # Increment start_
                         start_ = end
             else:
                 end += self._get_variable_size(variable)
 
             # Add to slices
-            y_slices[variable.id].append(slice(start, end))
+            y_slices[variable].append(slice(start, end))
             y_slices_explicit[variable].append(slice(start, end))
             # Add to bounds
             lower_bounds.extend([variable.bounds[0]] * (end - start))
@@ -363,7 +363,7 @@ def set_external_variables(self, model):
             # Find the name in the model variables
             # Look up dictionary key based on value
             try:
-                idx = [x.id for x in model.variables.values()].index(var.id)
+                idx = list(model.variables.values()).index(var)
             except ValueError:
                 raise ValueError(
                     """
@@ -423,8 +423,7 @@ def boundary_gradient(left_symbol, right_symbol):
                 left_symbol_disc, right_symbol_disc, left_mesh, right_mesh
             )
 
-        # bc_key_ids = [key.id for key in list(model.boundary_conditions.keys())]
-        bc_key_ids = list(self.bcs.keys())
+        bc_keys = list(self.bcs.keys())
 
         internal_bcs = {}
         for var in model.boundary_conditions.keys():
@@ -434,24 +433,24 @@ def boundary_gradient(left_symbol, right_symbol):
                 first_child = children[0]
                 next_child = children[1]
 
-                lbc = self.bcs[var.id]["left"]
+                lbc = self.bcs[var]["left"]
                 rbc = (boundary_gradient(first_child, next_child), "Neumann")
 
-                if first_child.id not in bc_key_ids:
-                    internal_bcs.update({first_child.id: {"left": lbc, "right": rbc}})
+                if first_child not in bc_keys:
+                    internal_bcs.update({first_child: {"left": lbc, "right": rbc}})
 
                 for current_child, next_child in zip(children[1:-1], children[2:]):
                     lbc = rbc
                     rbc = (boundary_gradient(current_child, next_child), "Neumann")
-                    if current_child.id not in bc_key_ids:
+                    if current_child not in bc_keys:
                         internal_bcs.update(
-                            {current_child.id: {"left": lbc, "right": rbc}}
+                            {current_child: {"left": lbc, "right": rbc}}
                         )
 
                 lbc = rbc
-                rbc = self.bcs[var.id]["right"]
-                if children[-1].id not in bc_key_ids:
-                    internal_bcs.update({children[-1].id: {"left": lbc, "right": rbc}})
+                rbc = self.bcs[var]["right"]
+                if children[-1] not in bc_keys:
+                    internal_bcs.update({children[-1]: {"left": lbc, "right": rbc}})
 
         self.bcs.update(internal_bcs)
 
@@ -504,7 +503,7 @@ def process_boundary_conditions(self, model):
         # process and set pybamm.variables first incase required
         # in discrisation of other boundary conditions
         for key, bcs in model.boundary_conditions.items():
-            processed_bcs[key.id] = {}
+            processed_bcs[key] = {}
 
             # check if the boundary condition at the origin for sphere domains is other
             # than no flux
@@ -528,7 +527,7 @@ def process_boundary_conditions(self, model):
                 eqn, typ = bc
                 pybamm.logger.debug("Discretise {} ({} bc)".format(key, side))
                 processed_eqn = self.process_symbol(eqn)
-                processed_bcs[key.id][side] = (processed_eqn, typ)
+                processed_bcs[key][side] = (processed_eqn, typ)
 
         return processed_bcs
 
@@ -661,7 +660,7 @@ def create_mass_matrix(self, model):
         model_variables = model.rhs.keys()
         model_slices = []
         for v in model_variables:
-            model_slices.append(self.y_slices[v.id][0])
+            model_slices.append(self.y_slices[v][0])
         sorted_model_variables = [
             v for _, v in sorted(zip(model_slices, model_variables))
         ]
@@ -792,8 +791,6 @@ def process_dict(self, var_eqn_dict):
             if np.prod(eqn.shape_for_testing) == 1 and not isinstance(eqn_key, str):
                 eqn = pybamm.FullBroadcast(eqn, broadcast_domains=eqn_key.domains)
 
-            # note we are sending in the key.id here so we don't have to
-            # keep calling .id
             pybamm.logger.debug("Discretise {!r}".format(eqn_key))
 
             processed_eqn = self.process_symbol(eqn)
@@ -818,10 +815,10 @@ def process_symbol(self, symbol):
 
         """
         try:
-            return self._discretised_symbols[symbol.id]
+            return self._discretised_symbols[symbol]
         except KeyError:
             discretised_symbol = self._process_symbol(symbol)
-            self._discretised_symbols[symbol.id] = discretised_symbol
+            self._discretised_symbols[symbol] = discretised_symbol
             discretised_symbol.test_shape()
 
             # Assign mesh as an attribute to the processed variable
@@ -978,15 +975,15 @@ def _process_symbol(self, symbol):
 
         elif isinstance(symbol, pybamm.VariableDot):
             return pybamm.StateVectorDot(
-                *self.y_slices[symbol.get_variable().id],
+                *self.y_slices[symbol.get_variable()],
                 domains=symbol.domains,
             )
 
         elif isinstance(symbol, pybamm.Variable):
             # Check if variable is a standard variable or an external variable
-            if any(symbol.id == var.id for var in self.external_variables.values()):
+            if any(symbol == var for var in self.external_variables.values()):
                 # Look up dictionary key based on value
-                idx = [x.id for x in self.external_variables.values()].index(symbol.id)
+                idx = list(self.external_variables.values()).index(symbol)
                 name, parent_and_slice = list(self.external_variables.keys())[idx]
                 if parent_and_slice is None:
                     # Variable didn't come from a concatenation so we can just create a
@@ -1014,7 +1011,7 @@ def _process_symbol(self, symbol):
                 # can't be found. This should usually be caught earlier by
                 # model.check_well_posedness, but won't be if debug_mode is False
                 try:
-                    y_slices = self.y_slices[symbol.id]
+                    y_slices = self.y_slices[symbol]
                 except KeyError:
                     raise pybamm.ModelError(
                         """
@@ -1088,19 +1085,19 @@ def _concatenate_in_order(self, var_eqn_dict, check_complete=False, sparse=False
                 unpacked_variables.extend([symbol] + [var for var in symbol.children])
             else:
                 unpacked_variables.append(symbol)
-            slices.append(self.y_slices[symbol.id][0])
+            slices.append(self.y_slices[symbol][0])
 
         if check_complete:
             # Check keys from the given var_eqn_dict against self.y_slices
-            ids = {v.id for v in unpacked_variables}
-            external_id = {v.id for v in self.external_variables.values()}
+            unpacked_variables_set = set(unpacked_variables)
+            external_vars = set(self.external_variables.values())
             for var in self.external_variables.values():
-                child_ids = {child.id for child in var.children}
-                external_id = external_id.union(child_ids)
+                child_vars = set(var.children)
+                external_vars = external_vars.union(child_vars)
             y_slices_with_external_removed = set(self.y_slices.keys()).difference(
-                external_id
+                external_vars
             )
-            if ids != y_slices_with_external_removed:
+            if unpacked_variables_set != y_slices_with_external_removed:
                 given_variable_names = [v.name for v in var_eqn_dict.keys()]
                 raise pybamm.ModelError(
                     "Initial conditions are insufficient. Only "

pybamm/expression_tree/binary_operators.py

@@ -102,24 +102,11 @@ def _binary_new_copy(self, left, right):
         """
         return self._binary_evaluate(left, right)
 
-    def evaluate(self, t=None, y=None, y_dot=None, inputs=None, known_evals=None):
+    def evaluate(self, t=None, y=None, y_dot=None, inputs=None):
         """See :meth:`pybamm.Symbol.evaluate()`."""
-        if known_evals is not None:
-            id = self.id
-            try:
-                return known_evals[id], known_evals
-            except KeyError:
-                left, known_evals = self.left.evaluate(t, y, y_dot, inputs, known_evals)
-                right, known_evals = self.right.evaluate(
-                    t, y, y_dot, inputs, known_evals
-                )
-                value = self._binary_evaluate(left, right)
-                known_evals[id] = value
-                return value, known_evals
-        else:
-            left = self.left.evaluate(t, y, y_dot, inputs)
-            right = self.right.evaluate(t, y, y_dot, inputs)
-            return self._binary_evaluate(left, right)
+        left = self.left.evaluate(t, y, y_dot, inputs)
+        right = self.right.evaluate(t, y, y_dot, inputs)
+        return self._binary_evaluate(left, right)
 
     def _evaluate_for_shape(self):
         """See :meth:`pybamm.Symbol.evaluate_for_shape()`."""
@@ -181,7 +168,7 @@ def _diff(self, variable):
         diff = exponent * (base ** (exponent - 1)) * base.diff(variable)
         # derivative if variable is in the exponent (rare, check separately to avoid
         # unecessarily big tree)
-        if any(variable.id == x.id for x in exponent.pre_order()):
+        if any(variable == x for x in exponent.pre_order()):
             diff += (base ** exponent) * pybamm.log(base) * exponent.diff(variable)
         return diff
 
@@ -581,7 +568,7 @@ def _diff(self, variable):
         diff = left.diff(variable)
         # derivative if variable is in the right term (rare, check separately to avoid
         # unecessarily big tree)
-        if any(variable.id == x.id for x in right.pre_order()):
+        if any(variable == x for x in right.pre_order()):
             diff += -pybamm.Floor(left / right) * right.diff(variable)
         return diff
 
@@ -850,7 +837,7 @@ def simplified_addition(left, right):
     elif (
         isinstance(left, MatrixMultiplication)
         and isinstance(right, MatrixMultiplication)
-        and left.right.id == right.right.id
+        and left.right == right.right
     ):
         l_left, l_right = left.orphans
         r_left = right.orphans[0]
@@ -955,7 +942,7 @@ def simplified_subtraction(left, right):
         return pybamm.simplify_if_constant(Subtraction(left, right))
 
     # a symbol minus itself is 0s of the same shape
-    if left.id == right.id:
+    if left == right:
         return pybamm.zeros_like(left)
 
     if isinstance(right, pybamm.Addition) and left.is_constant():
@@ -1185,7 +1172,7 @@ def simplified_division(left, right):
         return left
 
     # a symbol divided by itself is 1s of the same shape
-    if left.id == right.id:
+    if left == right:
         return pybamm.ones_like(left)
 
     # anything multiplied by a matrix one returns itself if

pybamm/expression_tree/concatenations.py

@@ -98,23 +98,13 @@ def _concatenation_evaluate(self, children_eval):
         else:
             return self.concatenation_function(children_eval)
 
-    def evaluate(self, t=None, y=None, y_dot=None, inputs=None, known_evals=None):
+    def evaluate(self, t=None, y=None, y_dot=None, inputs=None):
         """See :meth:`pybamm.Symbol.evaluate()`."""
         children = self.children
-        if known_evals is not None:
-            if self.id not in known_evals:
-                children_eval = [None] * len(children)
-                for idx, child in enumerate(children):
-                    children_eval[idx], known_evals = child.evaluate(
-                        t, y, y_dot, inputs, known_evals
-                    )
-                known_evals[self.id] = self._concatenation_evaluate(children_eval)
-            return known_evals[self.id], known_evals
-        else:
-            children_eval = [None] * len(children)
-            for idx, child in enumerate(children):
-                children_eval[idx] = child.evaluate(t, y, y_dot, inputs)
-            return self._concatenation_evaluate(children_eval)
+        children_eval = [None] * len(children)
+        for idx, child in enumerate(children):
+            children_eval[idx] = child.evaluate(t, y, y_dot, inputs)
+        return self._concatenation_evaluate(children_eval)
 
     def create_copy(self):
         """See :meth:`pybamm.Symbol.new_copy()`."""
@@ -430,8 +420,7 @@ def simplified_concatenation(*children):
         # Create Concatenation to easily read domains
         concat = Concatenation(*children)
         if all(
-            isinstance(child, pybamm.Broadcast)
-            and child.child.id == children[0].child.id
+            isinstance(child, pybamm.Broadcast) and child.child == children[0].child
             for child in children
         ):
             unique_child = children[0].orphans[0]

pybamm/expression_tree/functions.py

@@ -70,15 +70,15 @@ def __str__(self):
 
     def diff(self, variable):
         """See :meth:`pybamm.Symbol.diff()`."""
-        if variable.id == self.id:
+        if variable == self:
             return pybamm.Scalar(1)
         else:
             children = self.orphans
             partial_derivatives = [None] * len(children)
             for i, child in enumerate(self.children):
                 # if variable appears in the function, differentiate
                 # function, and apply chain rule
-                if variable.id in [symbol.id for symbol in child.pre_order()]:
+                if variable in child.pre_order():
                     partial_derivatives[i] = self._function_diff(
                         children, i
                     ) * child.diff(variable)
@@ -142,22 +142,12 @@ def _function_jac(self, children_jacs):
 
         return jacobian
 
-    def evaluate(self, t=None, y=None, y_dot=None, inputs=None, known_evals=None):
+    def evaluate(self, t=None, y=None, y_dot=None, inputs=None):
         """See :meth:`pybamm.Symbol.evaluate()`."""
-        if known_evals is not None:
-            if self.id not in known_evals:
-                evaluated_children = [None] * len(self.children)
-                for i, child in enumerate(self.children):
-                    evaluated_children[i], known_evals = child.evaluate(
-                        t, y, y_dot, inputs, known_evals=known_evals
-                    )
-                known_evals[self.id] = self._function_evaluate(evaluated_children)
-            return known_evals[self.id], known_evals
-        else:
-            evaluated_children = [
-                child.evaluate(t, y, y_dot, inputs) for child in self.children
-            ]
-            return self._function_evaluate(evaluated_children)
+        evaluated_children = [
+            child.evaluate(t, y, y_dot, inputs) for child in self.children
+        ]
+        return self._function_evaluate(evaluated_children)
 
     def _evaluates_on_edges(self, dimension):
         """See :meth:`pybamm.Symbol._evaluates_on_edges()`."""

pybamm/expression_tree/operations/convert_to_casadi.py

@@ -37,12 +37,12 @@ def convert(self, symbol, t, y, y_dot, inputs):
             The converted symbol
         """
         try:
-            return self._casadi_symbols[symbol.id]
+            return self._casadi_symbols[symbol]
         except KeyError:
             # Change inputs to empty dictionary if it's None
             inputs = inputs or {}
             casadi_symbol = self._convert(symbol, t, y, y_dot, inputs)
-            self._casadi_symbols[symbol.id] = casadi_symbol
+            self._casadi_symbols[symbol] = casadi_symbol
 
             return casadi_symbol