refactor code into modules

src/pg_rad/dataloader/dataloader.py

@@ -0,0 +1,28 @@
+import logging
+
+import pandas as pd
+
+from pg_rad.exceptions import DataLoadError, InvalidCSVError
+
+logger = logging.getLogger(__name__)
+
+def load_data(filename: str) -> pd.DataFrame:
+    logger.debug(f"Attempting to load file: {filename}")
+
+    try:
+        df = pd.read_csv(filename, delimiter=',')
+
+    except FileNotFoundError as e:
+        logger.error(f"File not found: {filename}")
+        raise DataLoadError(f"File does not exist: {filename}") from e
+
+    except pd.errors.ParserError as e:
+        logger.error(f"Invalid CSV format: {filename}")
+        raise InvalidCSVError(f"Invalid CSV file: {filename}") from e
+
+    except Exception as e:
+        logger.exception(f"Unexpected error while loading {filename}")
+        raise DataLoadError("Unexpected error while loading data") from e
+
+    logger.debug(f"File loaded: {filename}")
+    return df