Simplify frame extraction

movement/validators/files.py

@@ -304,55 +304,15 @@ def _file_contains_valid_frame_numbers(self, attribute, value):
 
         # If 'frame' is a file_attribute for all files:
         # extract frame number
-        list_frame_numbers = []
         if all(["frame" in d for d in file_attributes_dicts]):
-            for k_i, k in enumerate(file_attributes_dicts):
-                try:
-                    list_frame_numbers.append(int(k["frame"]))
-                except Exception as e:
-                    raise log_error(
-                        ValueError,
-                        f"{df.filename.iloc[k_i]} (row {k_i}): "
-                        "'frame' file attribute cannot be cast as an integer. "
-                        f"Please review the file attributes: {k}.",
-                    ) from e
-
+            list_frame_numbers = (
+                self._extract_frame_numbers_from_file_attributes(
+                    df, file_attributes_dicts
+                )
+            )
         # else: extract frame number from filename.
         else:
-            for f_i, f in enumerate(df["filename"]):
-                # try compiling the frame regexp
-                try:
-                    regex_match = re.search(self.frame_regexp, f)
-                except re.error as e:
-                    raise log_error(
-                        re.error,
-                        "The provided regular expression for the frame "
-                        f"numbers ({self.frame_regexp}) could not be compiled."
-                        " Please review its syntax.",
-                    ) from e
-
-                # try extracting the frame number from the filename using the
-                # compiled regexp
-                try:
-                    list_frame_numbers.append(int(regex_match.group(1)))  # type: ignore
-                except AttributeError as e:
-                    raise log_error(
-                        AttributeError,
-                        f"{f} (row {f_i}): The frame regexp did not "
-                        "return any matches and a frame number could not "
-                        "be extracted from the filename. If included in "
-                        "the filename, the frame number is expected as a "
-                        "zero-padded integer before the file extension "
-                        "(e.g. 00234.png).",
-                    ) from e
-                except ValueError as e:
-                    raise log_error(
-                        ValueError,
-                        f"{f} (row {f_i}): "
-                        "The frame number extracted from the filename using "
-                        f"the provided regexp ({self.frame_regexp}) could not "
-                        "be cast as an integer.",
-                    ) from e
+            list_frame_numbers = self._extract_frame_numbers_using_regexp(df)
 
         # Check we have as many unique frame numbers as unique image files
         if len(set(list_frame_numbers)) != len(df.filename.unique()):
@@ -364,6 +324,63 @@ def _file_contains_valid_frame_numbers(self, attribute, value):
                 "file. ",
             )
 
+    def _extract_frame_numbers_from_file_attributes(
+        self, df, file_attributes_dicts
+    ):
+        """Get frame numbers from the 'frame' key under 'file_attributes'."""
+        list_frame_numbers = []
+        for k_i, k in enumerate(file_attributes_dicts):
+            try:
+                list_frame_numbers.append(int(k["frame"]))
+            except Exception as e:
+                raise log_error(
+                    ValueError,
+                    f"{df.filename.iloc[k_i]} (row {k_i}): "
+                    "'frame' file attribute cannot be cast as an integer. "
+                    f"Please review the file attributes: {k}.",
+                ) from e
+        return list_frame_numbers
+
+    def _extract_frame_numbers_using_regexp(self, df):
+        """Get frame numbers from the file names using the provided regexp."""
+        list_frame_numbers = []
+        for f_i, f in enumerate(df["filename"]):
+            # try compiling the frame regexp
+            try:
+                regex_match = re.search(self.frame_regexp, f)
+            except re.error as e:
+                raise log_error(
+                    re.error,
+                    "The provided regular expression for the frame "
+                    f"numbers ({self.frame_regexp}) could not be compiled."
+                    " Please review its syntax.",
+                ) from e
+
+            # try extracting the frame number from the filename using the
+            # compiled regexp
+            try:
+                list_frame_numbers.append(int(regex_match.group(1)))  # type: ignore
+            except AttributeError as e:
+                raise log_error(
+                    AttributeError,
+                    f"{f} (row {f_i}): The frame regexp did not "
+                    "return any matches and a frame number could not "
+                    "be extracted from the filename. If included in "
+                    "the filename, the frame number is expected as a "
+                    "zero-padded integer before the file extension "
+                    "(e.g. 00234.png).",
+                ) from e
+            except ValueError as e:
+                raise log_error(
+                    ValueError,
+                    f"{f} (row {f_i}): "
+                    "The frame number extracted from the filename using "
+                    f"the provided regexp ({self.frame_regexp}) could not "
+                    "be cast as an integer.",
+                ) from e
+
+        return list_frame_numbers
+
     @path.validator
     def _file_contains_tracked_bboxes(self, attribute, value):
         """Ensure that the VIA tracks .csv contains tracked bounding boxes.