dev: add try_gcs, split, and datadir parameter

src/evox/problems/neuroevolution/supervised_learning/tfds.py

@@ -1,5 +1,5 @@
 from dataclasses import field
-from typing import Any, Callable, List
+from typing import Any, Callable, List, Optional
 
 import grain.python as pygrain
 import jax
@@ -45,6 +45,9 @@ class TensorflowDataset(Problem):
     namely JAX or Numpy arrays, or Python's int, float, list, and dict.
     If the data contains other types like strings, you should convert them into arrays using the `operations` parameter.
 
+    You can also download the dataset through a proxy server by setting the environment variable `TFDS_HTTP_PROXY` and `TFDS_HTTPS_PROXY`,
+    for http and https proxy respectively.
+
     The details of the dataset can be found at https://www.tensorflow.org/datasets/catalog/overview
     The details about operations/transformations can be found at https://github.com/google/grain/blob/main/docs/transformations.md
 
@@ -58,26 +61,49 @@ class TensorflowDataset(Problem):
         The loss function.
         The function signature is loss(weights, data) -> loss_value, and it should be jittable.
         The `weight` is the weight of the neural network, and the `data` is the data from TFDS, which is a dictionary.
+    split
+        Which split of the dataset to use.
+        Default to "train".
     operations
         The list of transformations to apply to the data.
         Default to [].
         After the transformations, we will always apply a batch operation to create a batch of data.
+    datadir
+        The directory to store the dataset.
+        Default to None, which means tensorflow-datasets will automatically determine the directory.
     seed
         The random seed used to seed the dataloader.
         Given the same seed, the dataloader should data in the same order.
         Default to 0.
+    try_gcs
+        Whether to try to download the dataset from Google Cloud Storage.
+        Usually Google's storage server is faster than the original server of the dataset.
     """
 
     dataset: Static[str]
     batch_size: Static[int]
     loss_func: Static[Callable]
+    split: Static[str] = field(default="train")
     operations: Static[List[Any]] = field(default_factory=list)
+    datadir: Static[Optional[str]] = field(default=None)
     seed: Static[int] = field(default=0)
+    try_gcs: Static[bool] = field(default=True)
     iterator: Static[pygrain.PyGrainDatasetIterator] = field(init=False)
     data_shape_dtypes: Static[Any] = field(init=False)
 
     def __post_init__(self):
-        data_source = tfds.data_source(self.dataset, split="train")
+        if self.datadir is None:
+            data_source = tfds.data_source(
+                self.dataset, try_gcs=self.try_gcs, split=self.split
+            )
+        else:
+            data_source = tfds.data_source(
+                self.dataset,
+                data_dir=self.datadir,
+                try_gcs=self.try_gcs,
+                split=self.split,
+            )
+
         sampler = pygrain.IndexSampler(
             num_records=len(data_source),
             shard_options=pygrain.NoSharding(),