[numerics] Improve documentation for TabulatedFunction

interfaces/cython/cantera/func1.pyx

@@ -110,25 +110,31 @@ cdef class TabulatedFunction(Func1):
     by two iterable objects containing sample point location and function
     values, or a single array that concatenates those inputs in two rows or
     columns. Between sample points, values are evaluated based on the optional
-    keyword argument 'method'; options are 'linear' (linear interpolation,
-    default) or 'previous' (nearest previous value). Outside the sample
+    keyword argument ``method``; options are ``'linear'`` (linear interpolation,
+    default) or ``'previous'`` (nearest previous value). Outside the sample
     interval, the value at the closest end point is returned.
 
-    Examples for `TabulatedFunction` objects are::
+    Examples for `TabulatedFunction` objects using a single (two-dimensional)
+    array as input are::
 
         >>> t1 = TabulatedFunction([[0, 2], [1, 1], [2, 0]])
         >>> [t1(v) for v in [-0.5, 0, 0.5, 1.5, 2, 2.5]]
         [2.0, 2.0, 1.5, 0.5, 0.0, 0.0]
 
-        >>> t2 = TabulatedFunction([[0, 2], [1, 1], [2, 0]], method='previous')
+        >>> t2 = TabulatedFunction(np.array([0, 1, 2]), (2, 1, 0))
         >>> [t2(v) for v in [-0.5, 0, 0.5, 1.5, 2, 2.5]]
-        [2.0, 2.0, 2.0, 1.0, 0.0, 0.0]
+        [2.0, 2.0, 1.5, 0.5, 0.0, 0.0]
 
-        >>> t3 = TabulatedFunction([0, 1, 2], [2, 1, 0])
+    where the optional ``method`` keyword argument changes the type of
+    interpolation from the ``'linear'`` default to ``'previous'``::
+
+        >>> t3 = TabulatedFunction([[0, 2], [1, 1], [2, 0]], method='previous')
         >>> [t3(v) for v in [-0.5, 0, 0.5, 1.5, 2, 2.5]]
-        [2.0, 2.0, 1.5, 0.5, 0.0, 0.0]
+        [2.0, 2.0, 2.0, 1.0, 0.0, 0.0]
+
+    Alternatively, a `TabulatedFunction` can be defined using two input arrays::
 
-        >>> t4 = TabulatedFunction(np.array([0, 1, 2]), (2, 1, 0))
+        >>> t4 = TabulatedFunction([0, 1, 2], [2, 1, 0])
         >>> [t4(v) for v in [-0.5, 0, 0.5, 1.5, 2, 2.5]]
         [2.0, 2.0, 1.5, 0.5, 0.0, 0.0]
     """
@@ -150,9 +156,8 @@ cdef class TabulatedFunction(Func1):
                                      "requires two rows or columns")
                 self._set_tables(time, fval, stringify(method))
             else:
-                raise TypeError(
-                    "'TabulatedFunction' must be constructed from "
-                    "a numeric array with two columns")
+                raise TypeError("'TabulatedFunction' must be constructed from "
+                                "a numeric array with two dimensions")
 
         elif len(args) == 2:
             # tabulated function (two arrays mimic C++ interface)

interfaces/cython/cantera/test/test_func1.py

@@ -119,4 +119,4 @@ def test_tabulated_failures(self):
         with self.assertRaisesRegex(ct.CanteraError, 'monotonically'):
             ct.TabulatedFunction((0, 1, 0.5, 2), (2, 1, 1, 0))
         with self.assertRaisesRegex(ct.CanteraError, 'not implemented'):
-            ct.TabulatedFunction((0, 1, 1, 2), (2, 1, 1, 0), method='quadratic')
+            ct.TabulatedFunction((0, 1, 1, 2), (2, 1, 1, 0), method='not implemented')