Clean up imports and apply suggested changes in drawnetwork.py

interfaces/cython/cantera/drawnetwork.py

@@ -1,8 +1,8 @@
 # This file is part of Cantera. See License.txt in the top-level directory or
 # at https://cantera.org/license.txt for license and copyright information.
 
-import importlib.metadata
-from functools import wraps
+import importlib.metadata as _metadata
+from functools import wraps as _wraps
 
 _graphviz = None
 def _import_graphviz():
@@ -11,16 +11,18 @@ def _import_graphviz():
     if _graphviz is not None:
         return
     try:
-        importlib.metadata.version("graphviz")
-    except importlib.metadata.PackageNotFoundError:
-        raise ImportError("This requires the graphviz package.")
+        _metadata.version("graphviz")
+    except _metadata.PackageNotFoundError:
+        raise ImportError("This requires a python interface to graphviz.\n"
+                          "It can be installed using conda (``conda install "
+                          "python-graphviz``) or pip (``pip install graphviz``)")
     else:
         import graphviz as _graphviz
 
 
-def needs_graphviz(func):
+def _needs_graphviz(func):
     # decorator function to load graphviz when needed
-    @wraps(func)
+    @_wraps(func)
     def inner(*args, **kwargs):
         if not _graphviz:
             _import_graphviz()
@@ -29,7 +31,7 @@ def needs_graphviz(func):
     return inner
 
 
-@needs_graphviz
+@_needs_graphviz
 def draw_reactor(r, dot=None, print_state=False, species=None, **kwargs):
     """
     Draw `ReactorBase` object as ``graphviz`` ``dot`` node.
@@ -72,11 +74,11 @@ def draw_reactor(r, dot=None, print_state=False, species=None, **kwargs):
         s_label = ""
 
         if species == "X":
-            X = r.thermo.mole_fraction_dict()
+            X = r.thermo.mole_fraction_dict(1e-4)
             s_percents = "\\n".join([f"{s}: {v*100:.2f}" for s, v in X.items()])
             s_label += "X (%)\\n" + s_percents
         elif species == "Y":
-            Y = r.thermo.mass_fraction_dict()
+            Y = r.thermo.mass_fraction_dict(1e-4)
             s_percents = "\\n".join([f"{s}: {v*100:.2f}" for s, v in Y.items()])
             s_label += "Y (%)\\n" + s_percents
         else:
@@ -87,11 +89,11 @@ def draw_reactor(r, dot=None, print_state=False, species=None, **kwargs):
                 s_label += "X (%)\\n" + s_percents
 
         # For full state output, shape must be 'Mrecord'
-        node_attr = {k:v for k,v in node_attr.items() if k != "shape"}
+        node_attr.pop("shape", None)
         dot.node(r.name, shape="Mrecord",
-                         label="{"+ T_label +"|"+ P_label +"}"+"|"+ s_label,
-                         xlabel=r.name,
-                         **node_attr)
+                 label=f"{{{T_label}|{P_label}}}|{s_label}",
+                 xlabel=r.name,
+                 **node_attr)
 
     else:
         dot.node(r.name, **node_attr)
@@ -99,7 +101,7 @@ def draw_reactor(r, dot=None, print_state=False, species=None, **kwargs):
     return dot
 
 
-@needs_graphviz
+@_needs_graphviz
 def draw_reactor_net(n, **kwargs):
     """
     Draw `ReactorNet` object as ``graphviz.graphs.DiGraph``. Connecting flow
@@ -130,7 +132,7 @@ def draw_reactor_net(n, **kwargs):
             draw_surface(surface, dot, **kwargs)
 
     # some Reactors or Reservoirs only exist as connecting nodes
-    connected_reactors = get_connected_reactors(connections)
+    connected_reactors = _get_connected_reactors(connections)
 
     # remove already drawn reactors and draw new reactors
     connected_reactors.difference_update(reactors)
@@ -142,7 +144,7 @@ def draw_reactor_net(n, **kwargs):
     return dot
 
 
-def get_connected_reactors(connections):
+def _get_connected_reactors(connections):
     """
     Collect and returned all connected reactors.
 
@@ -198,7 +200,9 @@ def draw_surface(surface, dot=None, **kwargs):
     dot.edge(r.name, name, **edge_attr)
 
     return dot
-def draw_connections(connections, dot=None, **kwargs):
+
+
+@_needs_graphviz
 def draw_connections(connections, dot=None, show_wall_velocity=True, **kwargs):
     """
     Draw connections between reactors and reservoirs. This includes flow
@@ -209,7 +213,7 @@ def draw_connections(connections, dot=None, show_wall_velocity=True, **kwargs):
         `FlowDevice` or `WallBase`.
     :param dot:
         ``graphviz.graphs.BaseGraph`` object to which the connection is added.
-        If not provided, a new ``DiGraph`` is created. Defaults to ``None``
+        If not provided, a new ``DiGraph`` is created. Defaults to ``None``.
     :param **kwargs:
         Keyword options can contain ``graph_attr`` and general ``node_attr``,
         ``edge_attr``, ``heat_flow_attr``, and ``mass_flow_attr`` to be passed

interfaces/cython/cantera/reactor.pyx

@@ -10,7 +10,7 @@ from .thermo cimport *
 from ._utils cimport pystr, stringify, comp_map, py_to_anymap, anymap_to_py
 from ._utils import *
 from .delegator cimport *
-from .drawnetwork import draw_reactor, draw_reactor_net, draw_connections
+from .drawnetwork import *
 
 _reactor_counts = _defaultdict(int)