[Python/examples] Suggestions from code review.

- don't make it look like unit tests
- print some output
- keep under 88 characters
- always create one solution, then save it in several formats

interfaces/cython/cantera/examples/onedim/flame_initial_guess.py

@@ -32,113 +32,123 @@
 # and may not be suitable for a publication-quality flame speed calculation
 refine_criteria = {"ratio": 3, "slope": 0.1, "curve": 0.2}
 f.set_refine_criteria(**refine_criteria)
-
-# Try to speed things up by loading the solution
-yaml_filepath = os.path.join(data_directory, "flame.yaml")
-try:
-    f.restore(yaml_filepath, name="solution", loglevel=0)
-except:
-    print("Couldn't load yaml solution, so starting from scratch")
-
 f.solve(loglevel=1, auto=True)
-print("mixture-averaged flame speed = {:7f} m/s\n".format(f.velocity[0]))
 
+def describe(flame):
+    "Print a short description of the flame, with a few properties."
+    print(f"Flame speed                    = {flame.velocity[0] * 100 :.2f} cm/s")
+    print(f"Maximum temperature            = {flame.T.max() :.0f} K")
+    # Find the location of the peak OH mole fraction
+    oh_index = flame.gas.species_index("OH")
+    grid_index = flame.X[oh_index].argmax()
+    oh_peak = flame.grid[grid_index]
+    print(f"Peak OH mole fraction location = {oh_peak * 100 :.2f} cm")
+    print(f"Solved with {flame.grid.size} grid points")
 
-def compare_flames(f1, f2):
-    """
-    Compare two flame solutions f1 and f2 and check that they're the same.
 
-    Expects the grids to be exactly the same, as if you have restored
-    the solution.
-    """
-    assert np.allclose(f1.grid, f2.grid), "Grid is different"
-    assert np.allclose(f1.T, f2.T), "Temperature profile is different"
-    assert np.allclose(f1.X[f.gas.species_index("CH4")], f2.X[f2.gas.species_index("CH4")] ), "Methane profile is different"
+describe(f)
 
-print("Save YAML and restore solution")
+# Save the flame in a few different formats
+print("Save YAML")
 yaml_filepath = os.path.join(data_directory, "flame.yaml")
 f.save(yaml_filepath, name="solution", description="Initial methane flame")
+
+print("Save CSV")
+csv_filepath = os.path.join(data_directory, "flame.csv")
+f.write_csv(csv_filepath)
+
+print("Save HDF")
+hdf_filepath = os.path.join(data_directory, "flame.h5")
+f.write_hdf(
+    hdf_filepath,
+    group="flame",
+    mode="w",
+    quiet=False,
+    description=("Initial methane flame"),
+)
+
+
+print("\nRestore solution from YAML")
 gas.TPX = Tin, p, reactants
 f2 = ct.FreeFlame(gas, width=width)
 f2.restore(yaml_filepath, name="solution", loglevel=0)
-compare_flames(f, f2)
+describe(f2)
 
-print("Save HDF and restore solution")
-hdf_filepath = os.path.join(data_directory, "flame.h5")
-f.write_hdf(hdf_filepath, group="flame", mode="w", quiet=False,
-            description=("Initial methane flame"))
+print("\nRestore solution from HDF")
 gas.TPX = Tin, p, reactants
 f2 = ct.FreeFlame(gas, width=width)
 f2.read_hdf(hdf_filepath, group="flame")
-compare_flames(f, f2)
+describe(f2)
 
-
-print("Save CSV then load initial guess via Pandas and SolutionArray")
-# In Cantera v2.6.0 passing set_initial_guess a Pandas DataFrame crashes so you
-# must use this work-around to create a SolutionArray from your DataFrame
-# and then pass the SolutionArray to the set_initial_guess method.
+print("\nLoad initial guess from CSV file directly")
 csv_filepath = os.path.join(data_directory, "flame.csv")
 f.write_csv(csv_filepath)
-df = pd.read_csv(csv_filepath)
-arr2 = ct.SolutionArray(gas)
-arr2.from_pandas(df)
-gas.TPX = Tin, p, reactants # must set the gas T back to the inlet before making new flame
+gas.TPX = Tin, p, reactants  # set the gas T back to the inlet before making new flame
 f2 = ct.FreeFlame(gas, width=width)
-f2.set_initial_guess(data=arr2)
-compare_flames(f, f2)
+f2.set_initial_guess(data=csv_filepath)
+describe(f2)
 
-print("Save CSV then load initial guess via Pandas")
+print("\nLoad initial guess from CSV file via Pandas")
 csv_filepath = os.path.join(data_directory, "flame.csv")
 f.write_csv(csv_filepath)
 df = pd.read_csv(csv_filepath)
-gas.TPX = Tin, p, reactants # must set the gas T back to the inlet before making new flame
+gas.TPX = Tin, p, reactants  # set the gas T back to the inlet before making new flame
 f2 = ct.FreeFlame(gas, width=width)
 f2.set_initial_guess(data=df)
-compare_flames(f, f2)
+describe(f2)
 
-print("Save CSV and load initial guess directly")
-# This one fails
-csv_filepath = os.path.join(data_directory, "flame.csv")
-f.write_csv(csv_filepath)
-gas.TPX = Tin, p, reactants # must set the gas T back to the inlet before making new flame
+
+print("\nLoad initial guess from CSV file via Pandas and SolutionArray")
+# In Cantera v2.6.0 passing set_initial_guess a Pandas DataFrame crashed so you
+# must use this work-around to create a SolutionArray from your DataFrame
+# and then pass the SolutionArray to the set_initial_guess method.
+df = pd.read_csv(csv_filepath)
+arr2 = ct.SolutionArray(gas)
+arr2.from_pandas(df)
+gas.TPX = Tin, p, reactants
+# set the gas T back to the inlet before making new flame
 f2 = ct.FreeFlame(gas, width=width)
-f2.set_initial_guess(data=csv_filepath)
-compare_flames(f, f2)
+f2.set_initial_guess(data=arr2)
+describe(f2)
 
-print("Save CSV then load initial guess via Pandas, with modifications")
-csv_filepath = os.path.join(data_directory, "flame.csv")
-f.write_csv(csv_filepath)
+
+print("\nLoad initial guess from CSV file via Pandas, with modifications.")
 df = pd.read_csv(csv_filepath)
-print("Modify the Pandas dataframe, removing half the grid points")
-df_pruned = df[::2] # remove half of the grid points
-gas.TPX = Tin, p, reactants # must set the gas T back to the inlet before making new flame
+print("\nModify the Pandas dataframe, removing half the grid points")
+df_pruned = df[::2]  # remove half of the grid points
+gas.TPX = Tin, p, reactants  # set the gas T back to the inlet before making new flame
 f2 = ct.FreeFlame(gas, width=width)
 f2.set_refine_criteria(**refine_criteria)
 f2.set_initial_guess(data=df_pruned)
 f2.solve()
-# We wouldn't expect the flame solutions to be exactly the same, so we just check a few other properties
-assert np.isclose(f.velocity[0], f2.velocity[0], 1e-2 ), "Flame speeds not within 1%"
-assert np.allclose(f.X.max(axis=1), f2.X.max(axis=1), rtol=0.2, atol=1e-20), "Max mole fractions not within 20%"
-
-print("Modify the Pandas dataframe, removing half the grid points and all but the first 20 species")
-df_pruned = df.iloc[::2,:24]
-gas.TPX = Tin, p, reactants # must set the gas T back to the inlet before making new flame
+# We wouldn't expect the flame solutions to be exactly the same
+describe(f2)
+
+print(
+    "\nModify the Pandas dataframe, removing half the grid points "
+    "and all but the first 20 species"
+)
+df_pruned = df.iloc[::2, :24]
+gas.TPX = Tin, p, reactants  # set the gas T back to the inlet before making new flame
 f2 = ct.FreeFlame(gas, width=width)
 f2.set_refine_criteria(**refine_criteria)
 f2.set_initial_guess(data=df_pruned)
 f2.solve()
-# We wouldn't expect the flame solutions to be exactly the same, so we just check a few other properties
-assert np.isclose(f.velocity[0], f2.velocity[0], 1e-2 ), "Flame speeds not within 1%"
-assert np.allclose(f.X.max(axis=1), f2.X.max(axis=1), rtol=0.2, atol=1e-20), "Max mole fractions not within 20%"
+# We wouldn't expect the flame solutions to be exactly the same
+describe(f2)
 
-print("Modify the Pandas dataframe, removing half the grid points, and raise the T by 50 K")
+print(
+    "\nModify the Pandas dataframe, removing half the grid points, "
+    "and raise the T by 50 K"
+)
 df_pruned = df.iloc[::2]
-gas.TPX = Tin + 50, p, reactants # must set the gas T back to the (new) inlet before making new flame
+# set the gas T back to the (new) inlet before making new flame
+gas.TPX = (Tin + 50, p, reactants)
 f2 = ct.FreeFlame(gas, width=width)
 f2.set_refine_criteria(**refine_criteria)
 f2.set_initial_guess(data=df_pruned)
 f2.solve()
 # We expect thees flames to be different because we raised the temperature.
-assert  f2.velocity[0] / f.velocity[0] > 1.1, "Flame speed hasn't increased by more than 10%"
+describe(f2)
 
-print("All done")
+print("\nAll done")