fix: Add embed_storage in Pdf feature

src/datasets/features/pdf.py

@@ -9,7 +9,7 @@
 from ..download.download_config import DownloadConfig
 from ..table import array_cast
 from ..utils.file_utils import is_local_path, xopen
-from ..utils.py_utils import string_to_dict
+from ..utils.py_utils import no_op_if_value_is_null, string_to_dict
 
 
 if TYPE_CHECKING:
@@ -216,6 +216,38 @@ def cast_storage(self, storage: Union[pa.StringArray, pa.StructArray, pa.ListArr
             storage = pa.StructArray.from_arrays([bytes_array, path_array], ["bytes", "path"], mask=storage.is_null())
         return array_cast(storage, self.pa_type)
 
+    def embed_storage(self, storage: pa.StructArray) -> pa.StructArray:
+        """Embed PDF files into the Arrow array.
+
+        Args:
+            storage (`pa.StructArray`):
+                PyArrow array to embed.
+
+        Returns:
+            `pa.StructArray`: Array in the PDF arrow storage type, that is
+                `pa.struct({"bytes": pa.binary(), "path": pa.string()})`.
+        """
+
+        @no_op_if_value_is_null
+        def path_to_bytes(path):
+            with xopen(path, "rb") as f:
+                bytes_ = f.read()
+            return bytes_
+
+        bytes_array = pa.array(
+            [
+                (path_to_bytes(x["path"]) if x["bytes"] is None else x["bytes"]) if x is not None else None
+                for x in storage.to_pylist()
+            ],
+            type=pa.binary(),
+        )
+        path_array = pa.array(
+            [os.path.basename(path) if path is not None else None for path in storage.field("path").to_pylist()],
+            type=pa.string(),
+        )
+        storage = pa.StructArray.from_arrays([bytes_array, path_array], ["bytes", "path"], mask=bytes_array.is_null())
+        return array_cast(storage, self.pa_type)
+
 
 def encode_pdfplumber_pdf(pdf: "pdfplumber.pdf.PDF") -> dict:
     """