Remove deprecated input-prep helpers and sklearn dependency (#506)

*Issue #, if available:*

*Description of changes:*
- Remove deprecated helpers in `_deprecated.py`
- Add informative error messages for deprecated methods
- Move `pandas[pyarrow]` to `extras`, install just `pandas` for the main
package
- Remove `sklearn` dependency


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choice.

Author: shchur

pyproject.toml

@@ -19,8 +19,7 @@ dependencies = [
   "accelerate>=1.1.0,<2",
   "numpy>=1.21,<3",
   "einops>=0.7.0,<1",
-  "scikit-learn>=1.6.0,<2",
-  "pandas[pyarrow]>=2.0,<2.4",
+  "pandas>=2.0,<2.4",
 ]
 classifiers = [
   "Programming Language :: Python :: 3",
@@ -44,6 +43,7 @@ extras = [
   "boto3>=1.10,<2",
   "peft>=0.18.1,<1",
   "fev>=0.6.1",
+  "pandas[pyarrow]>=2.0,<2.4",
 ]
 test = [
   "pytest~=8.0",
@@ -61,7 +61,6 @@ dev = [
   "joblib",
   "fev>=0.6.1",
   "rich",
-  "pandas>=2.0,<2.4",
 ]
 
 [project.urls]

src/chronos/base.py

@@ -12,12 +12,12 @@
 from typing import TYPE_CHECKING, Dict, List, Optional, Tuple, Union
 
 import numpy as np
+import pandas as pd
 import torch
 
 if TYPE_CHECKING:
     import datasets
     import fev
-    import pandas as pd
     from transformers import PreTrainedModel
 
 
@@ -134,7 +134,7 @@ def predict_quantiles(
 
     def predict_df(
         self,
-        df: "pd.DataFrame",
+        df: pd.DataFrame,
         *,
         id_column: str = "item_id",
         timestamp_column: str = "timestamp",
@@ -144,7 +144,7 @@ def predict_df(
         validate_inputs: bool = True,
         freq: str | None = None,
         **predict_kwargs,
-    ) -> "pd.DataFrame":
+    ) -> pd.DataFrame:
         """
         Perform forecasting on time series data in a long-format pandas DataFrame.
 
@@ -185,12 +185,7 @@ def predict_df(
         - "predictions": The point predictions generated by the model
         - One column for predictions at each quantile level in `quantile_levels`
         """
-        try:
-            import pandas as pd
-
-            from .df_utils import convert_df_input_to_list_of_dicts_input
-        except ImportError:
-            raise ImportError("pandas is required for predict_df. Please install it with `pip install pandas`.")
+        from .df_utils import convert_df_input_to_list_of_dicts_input
 
         if not isinstance(target, str):
             raise ValueError(

src/chronos/chronos2/_deprecated.py

@@ -12,12 +12,6 @@
 from torch.utils.data import IterableDataset
 
 from chronos.chronos2 import preprocess
-from chronos.chronos2._deprecated import (
-    convert_list_of_tensors_input_to_list_of_dicts_input,
-    convert_tensor_input_to_list_of_dicts_input,
-    prepare_inputs,
-    validate_and_prepare_single_dict_input,
-)
 from chronos.chronos2.preprocess import PreparedInput
 
 __all__ = [
@@ -27,11 +21,6 @@
     "convert_fev_window_to_list_of_dicts_input",
     "left_pad_and_cat_2D",
     "validate_prepared_schema",
-    # Deprecated re-exports — prefer chronos.chronos2.preprocess.from_* for new code.
-    "convert_list_of_tensors_input_to_list_of_dicts_input",
-    "convert_tensor_input_to_list_of_dicts_input",
-    "prepare_inputs",
-    "validate_and_prepare_single_dict_input",
 ]
 
 if TYPE_CHECKING:
@@ -434,3 +423,32 @@ def __iter__(self) -> Iterator:
                 yield batch
         else:
             yield from self._generate_sequential_batches()
+
+    @classmethod
+    def convert_inputs(cls, *args, **kwargs):
+        raise RuntimeError(
+            "`Chronos2Dataset.convert_inputs` has been deprecated. "
+            "Please use the `chronos.chronos2.preprocess` module instead."
+        )
+
+
+# Deprecated methods
+def validate_and_prepare_single_dict_task(*args, **kwargs):
+    raise RuntimeError(
+        "`validate_and_prepare_single_dict_task` has been deprecated. "
+        "Please use `chronos.chronos2.preprocess.from_list_of_dicts` instead."
+    )
+
+
+def convert_list_of_tensors_input_to_list_of_dicts_input(*args, **kwargs):
+    raise RuntimeError(
+        "`convert_list_of_tensors_input_to_list_of_dicts_input` has been deprecated. "
+        "Please use `chronos.chronos2.preprocess.from_list_of_tensors` instead."
+    )
+
+
+def convert_tensor_input_to_list_of_dicts_input(*args, **kwargs):
+    raise RuntimeError(
+        "`convert_tensor_input_to_list_of_dicts_input` has been deprecated. "
+        "Please use `chronos.chronos2.preprocess.from_tensor` instead."
+    )