Deprecate task api (#5865)

* Deprecate Task API

* Typo

* Update task_templates.mdx

* Update task_templates.mdx

Author: mariosasko

docs/source/package_reference/task_templates.mdx

@@ -1,5 +1,11 @@
 # Task templates
 
+<Tip warning={true}>
+
+The Task API is deprecated in favor of [`train-eval-index`](https://github.com/huggingface/hub-docs/blob/9ab2555e1c146122056aba6f89af404a8bc9a6f1/datasetcard.md?plain=1#L90-L106) and will be removed in the next major release.
+
+</Tip>
+
 The tasks supported by [`Dataset.prepare_for_task`] and [`DatasetDict.prepare_for_task`].
 
 [[autodoc]] datasets.tasks.AutomaticSpeechRecognition

src/datasets/arrow_dataset.py

@@ -109,6 +109,7 @@
 )
 from .tasks import TaskTemplate
 from .utils import logging
+from .utils.deprecation_utils import deprecated
 from .utils.file_utils import _retry, cached_path, estimate_dataset_size
 from .utils.hub import hf_hub_url
 from .utils.info_utils import is_small_dataset
@@ -2706,6 +2707,7 @@ def with_transform(
         dataset.set_transform(transform=transform, columns=columns, output_all_columns=output_all_columns)
         return dataset
 
+    @deprecated()
     def prepare_for_task(self, task: Union[str, TaskTemplate], id: int = 0) -> "Dataset":
         """
         Prepare a dataset for the given task by casting the dataset's [`Features`] to standardized column names and types as detailed in [`datasets.tasks`](./task_templates).

src/datasets/dataset_dict.py

@@ -25,6 +25,7 @@
 from .table import Table
 from .tasks import TaskTemplate
 from .utils import logging
+from .utils.deprecation_utils import deprecated
 from .utils.doc_utils import is_documented_by
 from .utils.file_utils import cached_path
 from .utils.hub import hf_hub_url
@@ -1537,6 +1538,7 @@ def from_text(
             path_or_paths, features=features, cache_dir=cache_dir, keep_in_memory=keep_in_memory, **kwargs
         ).read()
 
+    @deprecated()
     @is_documented_by(Dataset.prepare_for_task)
     def prepare_for_task(self, task: Union[str, TaskTemplate], id: int = 0) -> "DatasetDict":
         self._check_values_type()

src/datasets/load.py

@@ -63,7 +63,6 @@
     _hash_python_lines,
 )
 from .splits import Split
-from .tasks import TaskTemplate
 from .utils.deprecation_utils import deprecated
 from .utils.file_utils import (
     OfflineModeIsEnabled,
@@ -1586,7 +1585,7 @@ def load_dataset(
     revision: Optional[Union[str, Version]] = None,
     token: Optional[Union[bool, str]] = None,
     use_auth_token="deprecated",
-    task: Optional[Union[str, TaskTemplate]] = None,
+    task="deprecated",
     streaming: bool = False,
     num_proc: Optional[int] = None,
     storage_options: Optional[Dict] = None,
@@ -1708,6 +1707,12 @@ def load_dataset(
             </Deprecated>
         task (`str`):
             The task to prepare the dataset for during training and evaluation. Casts the dataset's [`Features`] to standardized column names and types as detailed in `datasets.tasks`.
+
+            <Deprecated version="2.13.0">
+
+            `task` was deprecated in version 2.13.0 and will be removed in 3.0.0.
+
+            </Deprecated>
         streaming (`bool`, defaults to `False`):
             If set to `True`, don't download the data files. Instead, it streams the data progressively while
             iterating on the dataset. An [`IterableDataset`] or [`IterableDatasetDict`] is returned instead in this case.
@@ -1795,6 +1800,13 @@ def load_dataset(
             f"You can remove this warning by passing 'verification_mode={verification_mode.value}' instead.",
             FutureWarning,
         )
+    if task != "deprecated":
+        warnings.warn(
+            "'task' was deprecated in version 2.13.0 and will be removed in 3.0.0.\n",
+            FutureWarning,
+        )
+    else:
+        task = None
     if data_files is not None and not data_files:
         raise ValueError(f"Empty 'data_files': '{data_files}'. It should be either non-empty or None (default).")
     if Path(path, config.DATASET_STATE_JSON_FILENAME).exists():
@@ -1855,7 +1867,10 @@ def load_dataset(
     ds = builder_instance.as_dataset(split=split, verification_mode=verification_mode, in_memory=keep_in_memory)
     # Rename and cast features to match task schema
     if task is not None:
-        ds = ds.prepare_for_task(task)
+        # To avoid issuing the same warning twice
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", FutureWarning)
+            ds = ds.prepare_for_task(task)
     if save_infos:
         builder_instance._save_infos()