fix: use a private cached function to recover the parquet database (#41)

pygaul/__init__.py

@@ -6,6 +6,7 @@
 import json
 import warnings
 from difflib import get_close_matches
+from functools import lru_cache
 from itertools import product
 from pathlib import Path
 from typing import List, Union
@@ -24,6 +25,12 @@
 __gaul_asset__ = "FAO/GAUL/2015/level{}"
 
 
+@lru_cache(maxsize=1)
+def _df() -> pd.DataFrame:
+    """Get the parquet database."""
+    return pd.read_parquet(__gaul_data__)
+
+
 @versionadded(version="0.3.0", reason="Add a Names object to handle names")
 class AdmNames(pd.DataFrame):
     def __init__(
@@ -49,7 +56,7 @@ def __init__(
 
         # if a name or admin number is set, we need to filter the dataset accordingly
         # if not we will simply consider the world dataset
-        df = pd.read_parquet(__gaul_data__)
+        df = _df()
         if name or admin:
             # set the id we look for and tell the function if its a name or an admin
             is_name = True if name else False