Add caching for Nordic country energy mix data

- Load and cache Nordic country energy mix data in _load_static_data()
- Add get_nordic_country_energy_mix_data() method to retrieve cached data
- This addresses the caching performance request in PR mlco2#1039

Author: Hinetziedacted

codecarbon/input.py

@@ -61,6 +61,11 @@ def _load_static_data() -> None:
     _CACHE["cpu_power"] = pd.read_csv(path)
 
 
+    # Nordic country energy mix - used for emissions calculations
+    path = _get_resource_path("data/private_infra/nordic_country_energy_mix.json")
+    with open(path) as f:
+        _CACHE["nordic_country_energy_mix"] = json.load(f)
+
 # Load static data at module import
 _load_static_data()
 
@@ -189,6 +194,13 @@ def get_cpu_power_data(self) -> pd.DataFrame:
         """
         return _CACHE["cpu_power"]
 
+    def get_nordic_country_energy_mix_data(self) -> Dict:
+        """
+        Returns Nordic Country Energy Mix Data.
+        Data is cached on first access per country.
+        """
+        return _CACHE["nordic_country_energy_mix"]
+
 
 class DataSourceException(Exception):
     pass