Revert task removal in folder-based builders (#5051)

* Add AudioClassification task

* Add classification task to folder based builders

* Fix tests

* Minor fix

* Minor fix again

docs/source/package_reference/task_templates.mdx

@@ -4,6 +4,8 @@ The tasks supported by [`Dataset.prepare_for_task`] and [`DatasetDict.prepare_fo
 
 [[autodoc]] datasets.tasks.AutomaticSpeechRecognition
 
+[[autodoc]] datasets.tasks.AudioClassification
+
 [[autodoc]] datasets.tasks.ImageClassification
     - align_with_features
 

src/datasets/packaged_modules/audiofolder/audiofolder.py

@@ -1,6 +1,7 @@
 from typing import List
 
 import datasets
+from datasets.tasks import AudioClassification
 
 from ..folder_based_builder import folder_based_builder
 
@@ -20,6 +21,7 @@ class AudioFolder(folder_based_builder.FolderBasedBuilder):
     BASE_COLUMN_NAME = "audio"
     BUILDER_CONFIG_CLASS = AudioFolderConfig
     EXTENSIONS: List[str]  # definition at the bottom of the script
+    CLASSIFICATION_TASK = AudioClassification(audio_column="audio", label_column="label")
 
 
 # Obtained with:

src/datasets/packaged_modules/folder_based_builder/folder_based_builder.py

@@ -2,14 +2,16 @@
 import itertools
 import os
 from dataclasses import dataclass
-from typing import Any, List, Optional, Tuple
+from typing import List, Optional, Tuple
 
 import pandas as pd
 import pyarrow as pa
 import pyarrow.compute as pc
 import pyarrow.json as paj
 
 import datasets
+from datasets.features.features import FeatureType
+from datasets.tasks.base import TaskTemplate
 
 
 logger = datasets.utils.logging.get_logger(__name__)
@@ -62,12 +64,14 @@ class FolderBasedBuilder(datasets.GeneratorBasedBuilder):
         BUILDER_CONFIG_CLASS: builder config inherited from `folder_based_builder.FolderBasedBuilderConfig`
         EXTENSIONS: list of allowed extensions (only files with these extensions and METADATA_FILENAME files
             will be included in a dataset)
+        CLASSIFICATION_TASK: classification task to use if labels are obtained from the folder structure
     """
 
-    BASE_FEATURE: Any
+    BASE_FEATURE: FeatureType
     BASE_COLUMN_NAME: str
     BUILDER_CONFIG_CLASS: FolderBasedBuilderConfig
     EXTENSIONS: List[str]
+    CLASSIFICATION_TASK: TaskTemplate
 
     SKIP_CHECKSUM_COMPUTATION_BY_DEFAULT: bool = True
     METADATA_FILENAMES: List[str] = ["metadata.csv", "metadata.jsonl"]
@@ -214,6 +218,7 @@ def analyze(files_or_archives, downloaded_files_or_dirs, split):
                         "label": datasets.ClassLabel(names=sorted(labels)),
                     }
                 )
+                self.info.task_templates = [self.CLASSIFICATION_TASK.align_with_features(self.info.features)]
             else:
                 self.info.features = datasets.Features({self.BASE_COLUMN_NAME: self.BASE_FEATURE})
 

src/datasets/packaged_modules/imagefolder/imagefolder.py

@@ -1,6 +1,7 @@
 from typing import List
 
 import datasets
+from datasets.tasks import ImageClassification
 
 from ..folder_based_builder import folder_based_builder
 
@@ -20,6 +21,7 @@ class ImageFolder(folder_based_builder.FolderBasedBuilder):
     BASE_COLUMN_NAME = "image"
     BUILDER_CONFIG_CLASS = ImageFolderConfig
     EXTENSIONS: List[str]  # definition at the bottom of the script
+    CLASSIFICATION_TASK = ImageClassification(image_column="image", label_column="label")
 
 
 # Obtained with:

src/datasets/tasks/__init__.py

@@ -1,6 +1,7 @@
 from typing import Optional
 
 from ..utils.logging import get_logger
+from .audio_classificiation import AudioClassification
 from .automatic_speech_recognition import AutomaticSpeechRecognition
 from .base import TaskTemplate
 from .image_classification import ImageClassification
@@ -12,6 +13,7 @@
 
 __all__ = [
     "AutomaticSpeechRecognition",
+    "AudioClassification",
     "ImageClassification",
     "LanguageModeling",
     "QuestionAnsweringExtractive",
@@ -25,6 +27,7 @@
 
 NAME2TEMPLATE = {
     AutomaticSpeechRecognition.task: AutomaticSpeechRecognition,
+    AudioClassification.task: AudioClassification,
     ImageClassification.task: ImageClassification,
     LanguageModeling.task: LanguageModeling,
     QuestionAnsweringExtractive.task: QuestionAnsweringExtractive,

src/datasets/tasks/audio_classificiation.py

@@ -0,0 +1,33 @@
+import copy
+from dataclasses import dataclass
+from typing import ClassVar, Dict
+
+from ..features import Audio, ClassLabel, Features
+from .base import TaskTemplate
+
+
+@dataclass(frozen=True)
+class AudioClassification(TaskTemplate):
+    task: str = "audio-classification"
+    input_schema: ClassVar[Features] = Features({"audio": Audio()})
+    label_schema: ClassVar[Features] = Features({"labels": ClassLabel})
+    audio_column: str = "audio"
+    label_column: str = "labels"
+
+    def align_with_features(self, features):
+        if self.label_column not in features:
+            raise ValueError(f"Column {self.label_column} is not present in features.")
+        if not isinstance(features[self.label_column], ClassLabel):
+            raise ValueError(f"Column {self.label_column} is not a ClassLabel.")
+        task_template = copy.deepcopy(self)
+        label_schema = self.label_schema.copy()
+        label_schema["labels"] = features[self.label_column]
+        task_template.__dict__["label_schema"] = label_schema
+        return task_template
+
+    @property
+    def column_mapping(self) -> Dict[str, str]:
+        return {
+            self.audio_column: "audio",
+            self.label_column: "labels",
+        }

tests/packaged_modules/test_folder_based_builder.py

@@ -11,13 +11,15 @@
     FolderBasedBuilder,
     FolderBasedBuilderConfig,
 )
+from datasets.tasks import TextClassification
 
 
 class DummyFolderBasedBuilder(FolderBasedBuilder):
     BASE_FEATURE = None
     BASE_COLUMN_NAME = "base"
     BUILDER_CONFIG_CLASS = FolderBasedBuilderConfig
     EXTENSIONS = [".txt"]
+    CLASSIFICATION_TASK = TextClassification(text_column="base", label_column="label")
 
 
 @pytest.fixture

tests/test_tasks.py

@@ -5,6 +5,7 @@
 from datasets.features import Audio, ClassLabel, Features, Image, Sequence, Value
 from datasets.info import DatasetInfo
 from datasets.tasks import (
+    AudioClassification,
     AutomaticSpeechRecognition,
     ImageClassification,
     LanguageModeling,
@@ -126,6 +127,33 @@ def test_from_dict(self):
         self.assertEqual(label_schema, task.label_schema)
 
 
+class AudioClassificationTest(TestCase):
+    def setUp(self):
+        self.labels = sorted(["pos", "neg"])
+
+    def test_column_mapping(self):
+        task = AudioClassification(audio_column="input_audio", label_column="input_label")
+        self.assertDictEqual({"input_audio": "audio", "input_label": "labels"}, task.column_mapping)
+
+    def test_from_dict(self):
+        input_schema = Features({"audio": Audio()})
+        label_schema = Features({"labels": ClassLabel})
+        template_dict = {
+            "audio_column": "input_image",
+            "label_column": "input_label",
+        }
+        task = AudioClassification.from_dict(template_dict)
+        self.assertEqual("audio-classification", task.task)
+        self.assertEqual(input_schema, task.input_schema)
+        self.assertEqual(label_schema, task.label_schema)
+
+    def test_align_with_features(self):
+        task = AudioClassification(audio_column="input_audio", label_column="input_label")
+        self.assertEqual(task.label_schema["labels"], ClassLabel)
+        task = task.align_with_features(Features({"input_label": ClassLabel(names=self.labels)}))
+        self.assertEqual(task.label_schema["labels"], ClassLabel(names=self.labels))
+
+
 class ImageClassificationTest(TestCase):
     def setUp(self):
         self.labels = sorted(["pos", "neg"])