Actually allowing arbitrary sequence in from_nodes().

Towards #146.

Before, these factory constructor methods **assumed** `nodes` had
a shape, which was not required by the documentation.

src/python/bezier/_base.py

@@ -39,11 +39,7 @@ class Base:
     _degree = -1
 
     def __init__(self, nodes, _copy=True):
-        nodes_np = np.asarray(nodes, order="F")
-        if nodes_np.ndim != 2:
-            raise ValueError("Nodes must be 2-dimensional, not", nodes_np.ndim)
-
-        nodes_np = _lossless_to_float(nodes_np)
+        nodes_np = sequence_to_array(nodes)
         dimension, _ = nodes_np.shape
         self._dimension = dimension
         if _copy:
@@ -102,3 +98,26 @@ def _lossless_to_float(array):
         raise ValueError("Array cannot be converted to floating point")
 
     return converted
+
+
+def sequence_to_array(nodes):
+    """Convert a sequence to a Fortran-ordered ``np.float64`` NumPy array.
+
+    Args:
+        nodes (Sequence[Sequence[numbers.Number]]): The control points for a
+            shape. Must be convertible to a 2D NumPy array of floating point
+            values, where the columns are the nodes and the rows correspond to
+            each dimension the shape occurs in.
+
+    Returns:
+        numpy.ndarray: The converted array (or the original if already a
+        float array).
+
+    Raises:
+        ValueError: If the ``nodes`` are not 2D.
+    """
+    nodes_np = np.asarray(nodes, order="F")
+    if nodes_np.ndim != 2:
+        raise ValueError("Nodes must be 2-dimensional, not", nodes_np.ndim)
+
+    return _lossless_to_float(nodes_np)

src/python/bezier/curve.py

@@ -116,9 +116,10 @@ def from_nodes(cls, nodes, _copy=True):
         Returns:
             Curve: The constructed curve.
         """
-        _, num_nodes = nodes.shape
+        nodes_np = _base.sequence_to_array(nodes)
+        _, num_nodes = nodes_np.shape
         degree = cls._get_degree(num_nodes)
-        return cls(nodes, degree, _copy=_copy)
+        return cls(nodes_np, degree, _copy=_copy)
 
     @staticmethod
     def _get_degree(num_nodes):

src/python/bezier/surface.py

@@ -210,9 +210,10 @@ def from_nodes(cls, nodes, _copy=True):
         Returns:
             Surface: The constructed surface.
         """
-        _, num_nodes = nodes.shape
+        nodes_np = _base.sequence_to_array(nodes)
+        _, num_nodes = nodes_np.shape
         degree = cls._get_degree(num_nodes)
-        return cls(nodes, degree, _copy=_copy)
+        return cls(nodes_np, degree, _copy=_copy)
 
     @staticmethod
     def _get_degree(num_nodes):

tests/unit/test_curve.py

@@ -54,6 +54,15 @@ def test_from_nodes_factory(self):
         self.assertEqual(curve._dimension, 3)
         self.assertEqual(curve._nodes, nodes)
 
+    def test_from_nodes_factory_non_array(self):
+        nodes = [[1.0, 1.0, 2.0], [2.0, 3.0, 4.0]]
+        klass = self._get_target_class()
+        curve = klass.from_nodes(nodes)
+        self.assertIsInstance(curve, klass)
+        self.assertEqual(curve._degree, 2)
+        self.assertEqual(curve._dimension, 2)
+        self.assertTrue(np.all(curve._nodes == nodes))
+
     def test__get_degree(self):
         klass = self._get_target_class()
         self.assertEqual(0, klass._get_degree(1))

tests/unit/test_surface.py

@@ -73,6 +73,16 @@ def test_from_nodes_factory(self):
         self.assertEqual(surface._nodes, nodes)
         self.assertIsNone(surface._edges)
 
+    def test_from_nodes_factory_non_array(self):
+        nodes = [[0.0, 1.0, 2.0]]
+        klass = self._get_target_class()
+        surface = klass.from_nodes(nodes)
+        self.assertIsInstance(surface, klass)
+        self.assertEqual(surface._degree, 1)
+        self.assertEqual(surface._dimension, 1)
+        self.assertTrue(np.all(surface._nodes == nodes))
+        self.assertIsNone(surface._edges)
+
     def test___repr__(self):
         nodes = np.zeros((3, 15), order="F")
         surface = self._make_one(nodes, 4)