Merge pull request #1502 from priyanshuone6/sympy-binary

Add to_equation in Binary and Scalar

docs/source/expression_tree/binary_operator.rst

@@ -25,7 +25,7 @@ Binary Operators
 .. autoclass:: pybamm.Inner
   :members:
 
-.. autoclass:: pybamm.Heaviside
+.. autoclass:: pybamm.expression_tree.binary_operators._Heaviside
   :members:
 
 .. autoclass:: pybamm.EqualHeaviside

pybamm/expression_tree/array.py

@@ -2,12 +2,15 @@
 # NumpyArray class
 #
 import numpy as np
+import sympy
+from scipy.sparse import csr_matrix, issparse
+
 import pybamm
-from scipy.sparse import issparse, csr_matrix
 
 
 class Array(pybamm.Symbol):
-    """node in the expression tree that holds an tensor type variable
+    """
+    Node in the expression tree that holds an tensor type variable
     (e.g. :class:`numpy.array`)
 
     Parameters
@@ -54,12 +57,12 @@ def entries(self):
 
     @property
     def ndim(self):
-        """ returns the number of dimensions of the tensor"""
+        """returns the number of dimensions of the tensor."""
         return self._entries.ndim
 
     @property
     def shape(self):
-        """ returns the number of entries along each dimension"""
+        """returns the number of entries along each dimension."""
         return self._entries.shape
 
     @property
@@ -86,19 +89,19 @@ def entries_string(self, value):
                 self._entries_string = (entries.tobytes(),)
 
     def set_id(self):
-        """ See :meth:`pybamm.Symbol.set_id()`. """
+        """See :meth:`pybamm.Symbol.set_id()`."""
         self._id = hash(
             (self.__class__, self.name) + self.entries_string + tuple(self.domain)
         )
 
     def _jac(self, variable):
-        """ See :meth:`pybamm.Symbol._jac()`. """
+        """See :meth:`pybamm.Symbol._jac()`."""
         # Return zeros of correct size
         jac = csr_matrix((self.size, variable.evaluation_array.count(True)))
         return pybamm.Matrix(jac)
 
     def new_copy(self):
-        """ See :meth:`pybamm.Symbol.new_copy()`. """
+        """See :meth:`pybamm.Symbol.new_copy()`."""
         return self.__class__(
             self.entries,
             self.name,
@@ -108,13 +111,18 @@ def new_copy(self):
         )
 
     def _base_evaluate(self, t=None, y=None, y_dot=None, inputs=None):
-        """ See :meth:`pybamm.Symbol._base_evaluate()`. """
+        """See :meth:`pybamm.Symbol._base_evaluate()`."""
         return self._entries
 
     def is_constant(self):
-        """ See :meth:`pybamm.Symbol.is_constant()`. """
+        """See :meth:`pybamm.Symbol.is_constant()`."""
         return True
 
+    def to_equation(self):
+        """Returns the value returned by the node when evaluated."""
+        entries_list = self.entries.tolist()
+        return sympy.Array(entries_list)
+
 
 def linspace(start, stop, num=50, **kwargs):
     """