Fix parameter path bug in windows

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Bug fixes
 
+-   Parameters can now be imported from any given path in `Windows` ([#1900](https://github.com/pybamm-team/PyBaMM/pull/1900))
 -   Fixed initial conditions for the EC SEI model ([#1895](https://github.com/pybamm-team/PyBaMM/pull/1895))
 
 # [v21.12](https://github.com/pybamm-team/PyBaMM/tree/v21.11) - 2021-12-29

pybamm/parameters/parameter_values.py

@@ -942,8 +942,13 @@ def find_parameter(path):
         """Look for parameter file in the different locations
         in PARAMETER_PATH
         """
+        # Check for absolute path
+        if os.path.isfile(path) and os.path.isabs(path):
+            pybamm.logger.verbose(f"Using absolute path: '{path}'")
+            return path
         for location in pybamm.PARAMETER_PATH:
             trial_path = os.path.join(location, path)
             if os.path.isfile(trial_path):
+                pybamm.logger.verbose(f"Using path: '{location}' + '{path}'")
                 return trial_path
         raise FileNotFoundError("Could not find parameter {}".format(path))

pybamm/util.py

@@ -283,19 +283,38 @@ def load_function(filename):
     # Assign path to _ and filename to tail
     _, tail = os.path.split(filename)
 
+    # Store the current working directory
+    orig_dir = os.getcwd()
+
     # Strip absolute path to pybamm/input/example.py
     if "pybamm" in filename:
         root_path = filename[filename.rfind("pybamm") :]
+    # If the function is in the current working directory
     elif os.getcwd() in filename:
+        root_path = filename.replace(os.getcwd(), "")
+        # getcwd() returns "C:\\" when in the root drive and "C:\\a\\b\\c" otherwise
+        if root_path[0] == "\\" or root_path[0] == "/":
+            root_path = root_path[1:]
+    # If the function is not in the current working directory and the path provided is
+    # absolute
+    elif os.path.isabs(filename) and not os.getcwd() in filename:   # pragma: no cover
+        # Change directory to import the function
+        dir_path = os.path.split(filename)[0]
+        os.chdir(dir_path)
         root_path = filename.replace(os.getcwd(), "")
         root_path = root_path[1:]
     else:
         root_path = filename
 
     path = root_path.replace("/", ".")
     path = path.replace("\\", ".")
+    pybamm.logger.debug(
+        f"Importing function '{tail}' from file '{filename}' via path '{path}'"
+    )
     module_object = importlib.import_module(path)
 
+    # Revert back current working directory if it was changed
+    os.chdir(orig_dir)
     return getattr(module_object, tail)
 
 

tests/unit/test_parameters/test_parameter_values.py

@@ -60,6 +60,18 @@ def test_init(self):
         )
         self.assertEqual(param["Positive electrode porosity"], 0.3)
 
+        # from file, absolute path
+        param = pybamm.ParameterValues(
+            os.path.join(
+                pybamm.root_dir(),
+                "pybamm",
+                "input",
+                "parameters",
+                "lithium_ion/positive_electrodes/lico2_Marquis2019/parameters.csv",
+            )
+        )
+        self.assertEqual(param["Positive electrode porosity"], 0.3)
+
         # values vs chemistry
         with self.assertRaisesRegex(
             ValueError, "values and chemistry cannot both be None"