Convert to string when needed + faster .zstd

src/datasets/filesystems/compression.py

@@ -14,7 +14,7 @@ class BaseCompressedFileFileSystem(AbstractArchiveFileSystem):
         None  # protocol passed in prefix to the url. ex: "gzip", for gzip://file.txt::http://foo.bar/file.txt.gz
     )
     compression: str = None  # compression type in fsspec. ex: "gzip"
-    extension: str = None  # extension of the filename to strip. ex: "".gz" to get file.txt from file.txt.gz
+    extensions: list[str] = None  # extensions of the filename to strip. ex: ".gz" to get file.txt from file.txt.gz
 
     def __init__(
         self, fo: str = "", target_protocol: Optional[str] = None, target_options: Optional[dict] = None, **kwargs
@@ -90,31 +90,31 @@ class Bz2FileSystem(BaseCompressedFileFileSystem):
 
     protocol = "bz2"
     compression = "bz2"
-    extension = ".bz2"
+    extensions = [".bz2"]
 
 
 class GzipFileSystem(BaseCompressedFileFileSystem):
     """Read contents of GZIP file as a filesystem with one file inside."""
 
     protocol = "gzip"
     compression = "gzip"
-    extension = ".gz"
+    extensions = [".gz", ".gzip"]
 
 
 class Lz4FileSystem(BaseCompressedFileFileSystem):
     """Read contents of LZ4 file as a filesystem with one file inside."""
 
     protocol = "lz4"
     compression = "lz4"
-    extension = ".lz4"
+    extensions = [".lz4"]
 
 
 class XzFileSystem(BaseCompressedFileFileSystem):
     """Read contents of .xz (LZMA) file as a filesystem with one file inside."""
 
     protocol = "xz"
     compression = "xz"
-    extension = ".xz"
+    extensions = [".xz"]
 
 
 class ZstdFileSystem(BaseCompressedFileFileSystem):
@@ -124,4 +124,4 @@ class ZstdFileSystem(BaseCompressedFileFileSystem):
 
     protocol = "zstd"
     compression = "zstd"
-    extension = ".zst"
+    extensions = [".zst", ".zstd"]

src/datasets/packaged_modules/json/json.py

@@ -90,6 +90,20 @@ def _cast_table(self, pa_table: pa.Table) -> pa.Table:
             for column_name in set(self.config.features) - set(pa_table.column_names):
                 type = self.config.features.arrow_schema.field(column_name).type
                 pa_table = pa_table.append_column(column_name, pa.array([None] * len(pa_table), type=type))
+            # convert to string when needed
+            for i, column_name in enumerate(pa_table.column_names):
+                if pa.types.is_struct(pa_table[column_name].type) and self.config.features.get(
+                    column_name, None
+                ) == datasets.Value("string"):
+                    jsonl = (
+                        pa_table[column_name]
+                        .to_pandas(types_mapper=pd.ArrowDtype)
+                        .to_json(orient="records", lines=True)
+                    )
+                    string_array = pa.array(
+                        ("{" + x.rstrip() for x in ("\n" + jsonl).split("\n{") if x), type=pa.string()
+                    )
+                    pa_table = pa_table.set_column(i, column_name, string_array)
             # more expensive cast to support nested structures with keys in a different order
             # allows str <-> int/float or str to Audio for example
             pa_table = table_cast(pa_table, self.config.features.arrow_schema)

src/datasets/utils/file_utils.py

@@ -461,12 +461,18 @@ def readline(f: io.RawIOBase):
 ]
 COMPRESSION_EXTENSION_TO_PROTOCOL = {
     # single file compression
-    **{fs_class.extension.lstrip("."): fs_class.protocol for fs_class in COMPRESSION_FILESYSTEMS},
+    **{
+        extension.lstrip("."): fs_class.protocol
+        for fs_class in COMPRESSION_FILESYSTEMS
+        for extension in fs_class.extensions
+    },
     # archive compression
     "zip": "zip",
 }
 SINGLE_FILE_COMPRESSION_EXTENSION_TO_PROTOCOL = {
-    fs_class.extension.lstrip("."): fs_class.protocol for fs_class in COMPRESSION_FILESYSTEMS
+    extension.lstrip("."): fs_class.protocol
+    for fs_class in COMPRESSION_FILESYSTEMS
+    for extension in fs_class.extensions
 }
 SINGLE_FILE_COMPRESSION_PROTOCOLS = {fs_class.protocol for fs_class in COMPRESSION_FILESYSTEMS}
 SINGLE_SLASH_AFTER_PROTOCOL_PATTERN = re.compile(r"(?<!:):/")