Index: trunk/SDToolBox/extract_waves.py
===================================================================
diff -u -r30 -r31
--- trunk/SDToolBox/extract_waves.py	(.../extract_waves.py)	(revision 30)
+++ trunk/SDToolBox/extract_waves.py	(.../extract_waves.py)	(revision 31)
@@ -170,10 +170,12 @@
         """
         nn_lon_idx = []
         nn_lat_idx = []
-        # TODO: this should be dynamic, not hardcoded.
-        base_file_name = 'Hs\\era5_Global_Hs_1981.nc'
-        ref_file_path = os.path.join(directory_path, base_file_name)
 
+        ref_file_path = self.find_default_file(directory_path)
+        # Hardcoded:
+        # base_file_name = 'Hs\\era5_Global_Hs_1981.nc'
+        # ref_file_path = os.path.join(directory_path, base_file_name)
+
         # Extract index and value for all input lat, lon.
         with Dataset(ref_file_path, 'r', self.__ds_format) \
                 as ref_dataset:
@@ -194,6 +196,13 @@
         return nn_lon_idx, nn_lat_idx
 
     @staticmethod
+    def find_default_file(dir: str):
+        for root, dirs, files in os.walk(dir):
+            for file in files:
+                if file.endswith('.nc'):
+                    return os.path.join(root, file)
+
+    @staticmethod
     def get_case_subset(dataset, variable_name, lon, lat):
         return dataset[variable_name][:, lat, lon]