feat: add pneumoniamnist builder

Author: CristianoPizzamiglio

tensorflow_datasets/image_classification/pneumoniamnist/pneumoniamnist_dataset_builder.py

@@ -0,0 +1,47 @@
+"""pneumoniamnist dataset."""
+
+import tensorflow_datasets.public_api as tfds
+
+
+class Builder(tfds.core.GeneratorBasedBuilder):
+  """DatasetBuilder for pneumoniamnist dataset."""
+
+  VERSION = tfds.core.Version('1.0.0')
+  RELEASE_NOTES = {
+      '1.0.0': 'Initial release.',
+  }
+
+  def _info(self) -> tfds.core.DatasetInfo:
+    """Returns the dataset metadata."""
+    # TODO(pneumoniamnist): Specifies the tfds.core.DatasetInfo object
+    return self.dataset_info_from_configs(
+        features=tfds.features.FeaturesDict({
+            # These are the features of your dataset like images, labels ...
+            'image': tfds.features.Image(shape=(None, None, 3)),
+            'label': tfds.features.ClassLabel(names=['no', 'yes']),
+        }),
+        # If there's a common (input, target) tuple from the
+        # features, specify them here. They'll be used if
+        # `as_supervised=True` in `builder.as_dataset`.
+        supervised_keys=('image', 'label'),  # Set to `None` to disable
+        homepage='https://dataset-homepage/',
+    )
+
+  def _split_generators(self, dl_manager: tfds.download.DownloadManager):
+    """Returns SplitGenerators."""
+    # TODO(pneumoniamnist): Downloads the data and defines the splits
+    path = dl_manager.download_and_extract('https://todo-data-url')
+
+    # TODO(pneumoniamnist): Returns the Dict[split names, Iterator[Key, Example]]
+    return {
+        'train': self._generate_examples(path / 'train_imgs'),
+    }
+
+  def _generate_examples(self, path):
+    """Yields examples."""
+    # TODO(pneumoniamnist): Yields (key, example) tuples from the dataset
+    for f in path.glob('*.jpeg'):
+      yield 'key', {
+          'image': f,
+          'label': 'yes',
+      }