add split argument to Generator

src/datasets/arrow_dataset.py

@@ -1068,6 +1068,7 @@ def from_generator(
         keep_in_memory: bool = False,
         gen_kwargs: Optional[dict] = None,
         num_proc: Optional[int] = None,
+        split: NamedSplit = Split.TRAIN,
         **kwargs,
     ):
         """Create a Dataset from a generator.
@@ -1090,6 +1091,10 @@ def from_generator(
                 If `num_proc` is greater than one, then all list values in `gen_kwargs` must be the same length. These values will be split between calls to the generator. The number of shards will be the minimum of the shortest list in `gen_kwargs` and `num_proc`.
 
                 <Added version="2.7.0"/>
+            split ([`NamedSplit`], defaults to `Split.TRAIN`):
+                Split name to be assigned to the dataset.
+
+                <Added version="2.21.0"/>
             **kwargs (additional keyword arguments):
                 Keyword arguments to be passed to :[`GeneratorConfig`].
 
@@ -1126,6 +1131,7 @@ def from_generator(
             keep_in_memory=keep_in_memory,
             gen_kwargs=gen_kwargs,
             num_proc=num_proc,
+            split=split,
             **kwargs,
         ).read()
 

src/datasets/io/generator.py

@@ -1,6 +1,6 @@
 from typing import Callable, Optional
 
-from .. import Features
+from .. import Features, NamedSplit, Split
 from ..packaged_modules.generator.generator import Generator
 from .abc import AbstractDatasetInputStream
 
@@ -15,6 +15,7 @@ def __init__(
         streaming: bool = False,
         gen_kwargs: Optional[dict] = None,
         num_proc: Optional[int] = None,
+        split: NamedSplit = Split.TRAIN,
         **kwargs,
     ):
         super().__init__(
@@ -30,13 +31,14 @@ def __init__(
             features=features,
             generator=generator,
             gen_kwargs=gen_kwargs,
+            split=split,
             **kwargs,
         )
 
     def read(self):
         # Build iterable dataset
         if self.streaming:
-            dataset = self.builder.as_streaming_dataset(split="train")
+            dataset = self.builder.as_streaming_dataset(split=self.builder.config.split)
         # Build regular (map-style) dataset
         else:
             download_config = None
@@ -52,6 +54,6 @@ def read(self):
                 num_proc=self.num_proc,
             )
             dataset = self.builder.as_dataset(
-                split="train", verification_mode=verification_mode, in_memory=self.keep_in_memory
+                split=self.builder.config.split, verification_mode=verification_mode, in_memory=self.keep_in_memory
             )
         return dataset

src/datasets/iterable_dataset.py

@@ -19,7 +19,7 @@
 from .features.features import FeatureType, _align_features, _check_if_features_can_be_aligned, cast_to_python_objects
 from .formatting import PythonFormatter, TensorFormatter, get_format_type_from_alias, get_formatter
 from .info import DatasetInfo
-from .splits import NamedSplit
+from .splits import NamedSplit, Split
 from .table import cast_table_to_features, read_schema_from_file, table_cast
 from .utils.logging import get_logger
 from .utils.py_utils import Literal
@@ -2083,6 +2083,7 @@ def from_generator(
         generator: Callable,
         features: Optional[Features] = None,
         gen_kwargs: Optional[dict] = None,
+        split: NamedSplit = Split.TRAIN,
     ) -> "IterableDataset":
         """Create an Iterable Dataset from a generator.
 
@@ -2095,7 +2096,10 @@ def from_generator(
                 Keyword arguments to be passed to the `generator` callable.
                 You can define a sharded iterable dataset by passing the list of shards in `gen_kwargs`.
                 This can be used to improve shuffling and when iterating over the dataset with multiple workers.
+            split ([`NamedSplit`], defaults to `Split.TRAIN`):
+                Split name to be assigned to the dataset.
 
+                <Added version="2.21.0"/>
         Returns:
             `IterableDataset`
 
@@ -2126,10 +2130,7 @@ def from_generator(
         from .io.generator import GeneratorDatasetInputStream
 
         return GeneratorDatasetInputStream(
-            generator=generator,
-            features=features,
-            gen_kwargs=gen_kwargs,
-            streaming=True,
+            generator=generator, features=features, gen_kwargs=gen_kwargs, streaming=True, split=split
         ).read()
 
     @staticmethod

src/datasets/packaged_modules/generator/generator.py

@@ -9,6 +9,7 @@ class GeneratorConfig(datasets.BuilderConfig):
     generator: Optional[Callable] = None
     gen_kwargs: Optional[dict] = None
     features: Optional[datasets.Features] = None
+    split: datasets.NamedSplit = datasets.Split.TRAIN
 
     def __post_init__(self):
         super().__post_init__()
@@ -26,7 +27,7 @@ def _info(self):
         return datasets.DatasetInfo(features=self.config.features)
 
     def _split_generators(self, dl_manager):
-        return [datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs=self.config.gen_kwargs)]
+        return [datasets.SplitGenerator(name=self.config.split, gen_kwargs=self.config.gen_kwargs)]
 
     def _generate_examples(self, **gen_kwargs):
         for idx, ex in enumerate(self.config.generator(**gen_kwargs)):

tests/test_arrow_dataset.py

@@ -3871,10 +3871,11 @@ def _gen():
     return _gen
 
 
-def _check_generator_dataset(dataset, expected_features):
+def _check_generator_dataset(dataset, expected_features, split):
     assert isinstance(dataset, Dataset)
     assert dataset.num_rows == 4
     assert dataset.num_columns == 3
+    assert dataset.split == split
     assert dataset.column_names == ["col_1", "col_2", "col_3"]
     for feature, expected_dtype in expected_features.items():
         assert dataset.features[feature].dtype == expected_dtype
@@ -3886,7 +3887,7 @@ def test_dataset_from_generator_keep_in_memory(keep_in_memory, data_generator, t
     expected_features = {"col_1": "string", "col_2": "int64", "col_3": "float64"}
     with assert_arrow_memory_increases() if keep_in_memory else assert_arrow_memory_doesnt_increase():
         dataset = Dataset.from_generator(data_generator, cache_dir=cache_dir, keep_in_memory=keep_in_memory)
-    _check_generator_dataset(dataset, expected_features)
+    _check_generator_dataset(dataset, expected_features, NamedSplit("train"))
 
 
 @pytest.mark.parametrize(
@@ -3907,7 +3908,23 @@ def test_dataset_from_generator_features(features, data_generator, tmp_path):
         Features({feature: Value(dtype) for feature, dtype in features.items()}) if features is not None else None
     )
     dataset = Dataset.from_generator(data_generator, features=features, cache_dir=cache_dir)
-    _check_generator_dataset(dataset, expected_features)
+    _check_generator_dataset(dataset, expected_features, NamedSplit("train"))
+
+
+@pytest.mark.parametrize(
+    "split",
+    [None, NamedSplit("train"), "train", NamedSplit("foo"), "foo"],
+)
+def test_dataset_from_generator_split(split, data_generator, tmp_path):
+    cache_dir = tmp_path / "cache"
+    default_expected_split = "train"
+    expected_features = {"col_1": "string", "col_2": "int64", "col_3": "float64"}
+    expected_split = split if split else default_expected_split
+    if split:
+        dataset = Dataset.from_generator(data_generator, cache_dir=cache_dir, split=split)
+    else:
+        dataset = Dataset.from_generator(data_generator, cache_dir=cache_dir)
+    _check_generator_dataset(dataset, expected_features, expected_split)
 
 
 @require_not_windows