add transforms

haferml/transforms/dataframe.py

@@ -0,0 +1,52 @@
+from __future__ import annotations
+from abc import ABC, abstractmethod
+import pandas as pd
+from typing import List, Union
+
+
+class TransformBase(ABC):
+    """
+    TransformBase transforms a dataframe.
+
+    This is a transformation inspired by the
+    package gluonts.
+    """
+
+    @abstractmethod
+    def __call__(self, dataframe: pd.DataFrame) -> pd.DataFrame:
+        """
+        """
+        raise NotImplementedError("This method is not implemented yet.")
+
+    def __add__(self, other: TransformBase) -> ConcatTransform:
+        """
+        """
+        return ConcatTransform([self, other])
+
+
+class ConcatTransform(TransformBase):
+    """Concatenated transforms.
+
+    The returned transforms inherited from the
+
+    :param transforms: List of transforms to be concatenated
+    """
+
+    def __init__(self, transforms: List[TransformBase]):
+        self.transforms = []
+        for transform in transforms:
+            self._update(transform)
+
+    def _update(self, transform: Union[ConcatTransform, TransformBase]):
+        if isinstance(transform, ConcatTransform):
+            self.transforms.extend(transform)
+        elif isinstance(transform, TransformBase):
+            self.transforms.append(transform)
+        else:
+            raise TypeError("Expected type TransformBase or ConcatTransform")
+
+    def __call__(self, dataframe: pd.DataFrame) -> pd.DataFrame:
+        for t in self.transforms:
+            dataframe = t(dataframe)
+
+        return dataframe

tests/transforms/test_base.py

@@ -0,0 +1,2 @@
+from haferml.transforms import BaseTransform
+