REF: Rename _Data.__i to more appropriate _Data.__len

Author: kernc

backtesting/_util.py

@@ -109,7 +109,7 @@ class _Data:
     """
     def __init__(self, df: pd.DataFrame):
         self.__df = df
-        self.__i = len(df)
+        self.__len = len(df)  # Current length
         self.__pip: Optional[float] = None
         self.__cache: Dict[str, _Array] = {}
         self.__arrays: Dict[str, _Array] = {}
@@ -124,8 +124,8 @@ def __getattr__(self, item):
         except KeyError:
             raise AttributeError(f"Column '{item}' not in data") from None
 
-    def _set_length(self, i):
-        self.__i = i
+    def _set_length(self, length):
+        self.__len = length
         self.__cache.clear()
 
     def _update(self):
@@ -136,18 +136,18 @@ def _update(self):
         self.__arrays['__index'] = index
 
     def __repr__(self):
-        i = min(self.__i, len(self.__df)) - 1
+        i = min(self.__len, len(self.__df)) - 1
         index = self.__arrays['__index'][i]
         items = ', '.join(f'{k}={v}' for k, v in self.__df.iloc[i].items())
         return f'<Data i={i} ({index}) {items}>'
 
     def __len__(self):
-        return self.__i
+        return self.__len
 
     @property
     def df(self) -> pd.DataFrame:
-        return (self.__df.iloc[:self.__i]
-                if self.__i < len(self.__df)
+        return (self.__df.iloc[:self.__len]
+                if self.__len < len(self.__df)
                 else self.__df)
 
     @property
@@ -160,7 +160,7 @@ def pip(self) -> float:
     def __get_array(self, key) -> _Array:
         arr = self.__cache.get(key)
         if arr is None:
-            arr = self.__cache[key] = cast(_Array, self.__arrays[key][:self.__i])
+            arr = self.__cache[key] = cast(_Array, self.__arrays[key][:self.__len])
         return arr
 
     @property