Add option to save difference curve

docs/source/morphpy.rst

@@ -38,7 +38,7 @@ Python Morphing Functions
 
        * ``morph_info`` contains all morphs as keys (e.g. ``"scale"``, ``"stretch"``, ``"smear"``) with
          the optimized morphing parameters found by ``diffpy.morph`` as values. ``morph_info`` also contains
-         the Rw and Pearson correlation coefficients found post-morphing. Try printing ``print(morph_info)``
+         the Rw and Pearson correlation coefficients found post-morphing. Try printing ``print(morph_info)``
          and compare the values stored in this dictionary to those given by the CLI output!
        * ``morph_table`` is a two-column array of the morphed function interpolated onto the grid of the
          target function (e.g. in our example, it returns the contents of `darkSub_rh20_C_01.gr` after
@@ -74,6 +74,10 @@ General Parameters
 
 save: str or path
     Save the morphed function to a the file passed to save. Use '-' for stdout.
+get_diff: bool
+    Return the difference function (morphed function minus target function) instead of
+    the morphed function (default). When save is enabled, the difference function
+    is saved instead of the morphed function.
 verbose: bool
     Print additional header details to saved files. These include details about the morph
     inputs and outputs.
@@ -240,4 +244,4 @@ As you can see, the fitted scale and offset values match the ones used
 to generate the target (scale=20 & offset=0.8). This example shows how
 ``MorphFuncy`` can be used to fit and apply custom transformations. Now
 it's your turn to experiment with other custom functions that may be useful
-for analyzing your data.
+for analyzing your data.

news/save_diff.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* There is now an option to save the difference curve. This is computed on the common interval between the two curves.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

src/diffpy/morph/morph_io.py

@@ -47,7 +47,7 @@ def single_morph_output(
     save_file
         Name of file to print to. If None (default) print to terminal.
     morph_file
-        Name of the morphed PDF file. Required when printing to a
+        Name of the morphed function file. Required when printing to a
         non-terminal file.
     param xy_out: list
         List of the form [x_morph_out, y_morph_out]. x_morph_out is a List of
@@ -144,7 +144,7 @@ def single_morph_output(
 
 
 def create_morphs_directory(save_directory):
-    """Create a directory for saving multiple morphed PDFs.
+    """Create a directory for saving multiple morphed functions.
 
     Takes in a user-given path to a directory save_directory and create a
     subdirectory named Morphs. diffpy.morph will save all morphs into the
@@ -183,7 +183,7 @@ def get_multisave_names(target_list: list, save_names_file=None, mm=False):
     Parameters
     ----------
     target_list: list
-        Target (or Morph if mm enabled) PDFs used for each morph.
+        Target (or Morph if mm enabled) functions used for each morph.
     save_names_file
         Name of file to import save names dictionary from (default None).
     mm: bool
@@ -192,8 +192,8 @@ def get_multisave_names(target_list: list, save_names_file=None, mm=False):
     Returns
     -------
     dict
-        The names to save each morph as. Keys are the target PDF file names
-        used to produce that morph.
+        The names to save each morph as. Keys are the target function file
+        names used to produce that morph.
     """
 
     # Dictionary storing save file names
@@ -252,20 +252,20 @@ def multiple_morph_output(
     morph_results: dict
         Resulting data after morphing.
     target_files: list
-        PDF files that acted as targets to morphs.
+        Files that acted as targets to morphs.
     save_directory
         Name of directory to save morphs in.
     field
         Name of field if data was sorted by a particular field.
         Otherwise, leave blank.
     field_list: list
-        List of field values for each target PDF.
+        List of field values for each target function.
         Generated by diffpy.morph.tools.field_sort().
     morph_file
-        Name of the morphed PDF file.
+        Name of the morphed function file.
         Required to give summary data after saving to a directory.
     target_directory
-        Name of the directory containing the target PDF files.
+        Name of the directory containing the target function files.
         Required to give summary data after saving to a directory.
     verbose: bool
         Print additional summary details when True (default False).

src/diffpy/morph/morphapp.py

@@ -81,14 +81,27 @@ def custom_error(self, msg):
         metavar="NAME",
         dest="slocation",
         help=(
-            "Save the manipulated PDF to a file named NAME. "
+            "Save the manipulated function to a file named NAME. "
             "Use '-' for stdout.\n"
             "When --multiple-<targets/morphs> is enabled, "
-            "save each manipulated PDF as a file in a directory named NAME;\n"
-            "you can specify names for each saved PDF file using "
+            "save each manipulated function as a file in a directory "
+            "named NAME;\n"
+            "you can specify names for each saved function file using "
             "--save-names-file."
         ),
     )
+    parser.add_option(
+        "--diff",
+        "--get-diff",
+        dest="get_diff",
+        action="store_true",
+        help=(
+            "Save the difference curve rather than the manipulated function.\n"
+            "This is computed as manipulated function minus target function.\n"
+            "The difference curve is computed on the interval shared by the "
+            "grid of the objective and target function."
+        ),
+    )
     parser.add_option(
         "-v",
         "--verbose",
@@ -99,12 +112,12 @@ def custom_error(self, msg):
     parser.add_option(
         "--rmin",
         type="float",
-        help="Minimum r-value to use for PDF comparisons.",
+        help="Minimum r-value (abscissa) to use for function comparisons.",
     )
     parser.add_option(
         "--rmax",
         type="float",
-        help="Maximum r-value to use for PDF comparisons.",
+        help="Maximum r-value (abscissa) to use for function comparisons.",
     )
     parser.add_option(
         "--tolerance",
@@ -419,9 +432,9 @@ def custom_error(self, msg):
             "using a serial file NAMESFILE. The format of NAMESFILE should be "
             "as follows: each target PDF is an entry in NAMESFILE. For each "
             "entry, there should be a key {__save_morph_as__} whose value "
-            "specifies the name to save the manipulated PDF as. An example "
-            ".json serial file is included in the tutorial directory "
-            "on the package GitHub repository."
+            "specifies the name to save the manipulated function as."
+            "An example .json serial file is included in the tutorial "
+            "directory on the package GitHub repository."
         ),
     )
     group.add_option(
@@ -492,10 +505,7 @@ def single_morph(
     smear_in = "None"
     hshift_in = "None"
     vshift_in = "None"
-    config = {}
-    config["rmin"] = opts.rmin
-    config["rmax"] = opts.rmax
-    config["rstep"] = None
+    config = {"rmin": opts.rmin, "rmax": opts.rmax, "rstep": None}
     if (
         opts.rmin is not None
         and opts.rmax is not None
@@ -708,13 +718,29 @@ def single_morph(
     morph_results.update({"Pearson": pcc})
 
     # Print summary to terminal and save morph to file if requested
+    xy_save = [chain.x_morph_out, chain.y_morph_out]
+    if opts.get_diff is not None:
+        diff_chain = morphs.MorphChain(
+            {"rmin": None, "rmax": None, "rstep": None}
+        )
+        diff_chain.append(morphs.MorphRGrid())
+        diff_chain(
+            chain.x_morph_out,
+            chain.y_morph_out,
+            chain.x_target_in,
+            chain.y_target_in,
+        )
+        xy_save = [
+            diff_chain.x_morph_out,
+            diff_chain.y_morph_out - diff_chain.y_target_out,
+        ]
     try:
         io.single_morph_output(
             morph_inputs,
             morph_results,
             save_file=opts.slocation,
             morph_file=pargs[0],
-            xy_out=[chain.x_morph_out, chain.y_morph_out],
+            xy_out=xy_save,
             verbose=opts.verbose,
             stdout_flag=stdout_flag,
         )
@@ -753,7 +779,7 @@ def single_morph(
     # Return different things depending on whether it is python interfaced
     if python_wrap:
         morph_info = morph_results
-        morph_table = numpy.array([chain.x_morph_out, chain.y_morph_out]).T
+        morph_table = numpy.array(xy_save).T
         return morph_info, morph_table
     else:
         return morph_results

src/diffpy/morph/morphpy.py

@@ -44,6 +44,8 @@ def __get_morph_opts__(parser, scale, stretch, smear, plot, **kwargs):
         "addpearson",
         "apply",
         "reverse",
+        "diff",
+        "get-diff",
     ]
     opts_to_ignore = ["multiple-morphs", "multiple-targets"]
     for opt in opts_storing_values:

tests/test_morphio.py

@@ -11,6 +11,7 @@
     single_morph,
 )
 from diffpy.morph.morphpy import morph_arrays
+from diffpy.utils.parsers.loaddata import loadData
 
 # Support Python 2
 try:
@@ -64,6 +65,29 @@ def are_files_same(file1, file2):
                 assert f1_arr[idx] == f2_arr[idx]
 
 
+def are_diffs_right(file1, file2, diff_file):
+    """Assert that diff_file ordinate data is approximately file1
+    ordinate data minus file2 ordinate data."""
+    f1_data = loadData(file1)
+    f2_data = loadData(file2)
+    diff_data = loadData(diff_file)
+
+    rmin = max(min(f1_data[:, 0]), min(f1_data[:, 1]))
+    rmax = min(max(f2_data[:, 0]), max(f2_data[:, 1]))
+    rnumsteps = max(
+        len(f1_data[:, 0][(rmin <= f1_data[:, 0]) & (f1_data[:, 0] <= rmax)]),
+        len(f2_data[:, 0][(rmin <= f2_data[:, 0]) & (f2_data[:, 0] <= rmax)]),
+    )
+
+    share_grid = np.linspace(rmin, rmax, rnumsteps)
+    f1_interp = np.interp(share_grid, f1_data[:, 0], f1_data[:, 1])
+    f2_interp = np.interp(share_grid, f2_data[:, 0], f2_data[:, 1])
+    diff_interp = np.interp(share_grid, diff_data[:, 0], diff_data[:, 1])
+
+    for idx, diff in enumerate(diff_interp):
+        assert np.isclose(f1_interp[idx] - f2_interp[idx], diff)
+
+
 class TestApp:
     @pytest.fixture
     def setup(self):
@@ -165,6 +189,59 @@ def test_morph_outputs(self, setup, tmp_path):
                     expected = filter(ignore_path, tf)
                     are_files_same(actual, expected)
 
+    # Similar format as test_morph_outputs
+    def test_morph_diff_outputs(self, setup, tmp_path):
+        morph_file = self.testfiles[0]
+        target_file = self.testfiles[-1]
+
+        # Save multiple diff morphs
+        tmp_diff = tmp_path.joinpath("diff")
+        tmp_diff_name = tmp_diff.resolve().as_posix()
+
+        (opts, pargs) = self.parser.parse_args(
+            [
+                "--multiple-targets",
+                "--sort-by",
+                "temperature",
+                "-s",
+                tmp_diff_name,
+                "-n",
+                "--save-names-file",
+                tssf,
+                "--diff",
+            ]
+        )
+        pargs = [morph_file, testsequence_dir]
+        multiple_targets(self.parser, opts, pargs, stdout_flag=False)
+
+        # Save a single diff morph
+        diff_name = "single_diff_morph.cgr"
+        diff_file = tmp_diff.joinpath(diff_name)
+        df_name = diff_file.resolve().as_posix()
+        (opts, pargs) = self.parser.parse_args(["-s", df_name, "-n", "--diff"])
+        pargs = [morph_file, target_file]
+        single_morph(self.parser, opts, pargs, stdout_flag=False)
+
+        # Check that the saved diff matches the morph minus target
+        # Morphs are saved in testdata/testsequence/testsaving/succinct
+        # Targets are stored in testdata/testsequence
+
+        # Single morph diff
+        morphed_file = test_saving_succinct / diff_name.replace(
+            "diff", "succinct"
+        )
+        are_diffs_right(morphed_file, target_file, diff_file)
+
+        # Multiple morphs diff
+        diff_files = list((tmp_diff / "Morphs").iterdir())
+        morphed_files = list((test_saving_succinct / "Morphs").iterdir())
+        target_files = self.testfiles[1:]
+        diff_files.sort()
+        morphed_files.sort()
+        target_files.sort()
+        for idx, diff_file in enumerate(diff_files):
+            are_diffs_right(morphed_files[idx], target_files[idx], diff_file)
+
     def test_morphsqueeze_outputs(self, setup, tmp_path):
         # The file squeeze_morph has a squeeze and stretch applied
         morph_file = testdata_dir / "squeeze_morph.cgr"

tests/test_morphpy.py

@@ -75,6 +75,7 @@ def test_morph_opts(self, setup_morph):
             "addpearson": False,
             "apply": False,
             "reverse": False,
+            "get_diff": False,
             "multiple_morphs": False,
             "multiple_targets": False,
         }
@@ -96,6 +97,7 @@ def test_morph_opts(self, setup_morph):
             "addpearson": True,
             "apply": True,
             "reverse": True,
+            "get_diff": True,
             "multiple_morphs": True,
             "multiple_targets": True,
         }