allow only one default compressor

Author: brokkoli71

src/zarr/api/asynchronous.py

@@ -822,7 +822,7 @@ async def create(
         - For numeric arrays, the default is `ZstdCodec`.
         - For Unicode strings, the default is `VLenUTF8Codec`.
         - For bytes or objects, the default is `VLenBytesCodec`.
-        These defaults can be changed using the `v2_default_compressors` variable in the Zarr config.
+        These defaults can be changed using the `v2_default_compressor` variable in the Zarr config.
     fill_value : object
         Default value to use for uninitialized portions of the array.
     order : {'C', 'F'}, optional
@@ -898,7 +898,7 @@ async def create(
         dtype = parse_dtype(dtype, zarr_format)
         if not filters and not compressor:
             filters, compressor = _default_filters_and_compressor(dtype)
-    elif zarr_format == 3 and chunk_shape is None: #type: ignore[redundant-expr]
+    elif zarr_format == 3 and chunk_shape is None:  # type: ignore[redundant-expr]
         if chunks is not None:
             chunk_shape = chunks
             chunks = None

src/zarr/core/config.py

@@ -64,10 +64,10 @@ def reset(self) -> None:
             },
             "buffer": "zarr.core.buffer.cpu.Buffer",
             "ndbuffer": "zarr.core.buffer.cpu.NDBuffer",
-            "v2_default_compressors": {
-                "numeric": ["zstd"],
-                "unicode": ["vlen-utf8"],
-                "bytes": ["vlen-bytes"],
+            "v2_default_compressor": {
+                "numeric": "zstd",
+                "string": "vlen-utf8",
+                "bytes": "vlen-bytes",
             },
         }
     ],

src/zarr/core/metadata/v2.py

@@ -337,14 +337,14 @@ def _default_filters_and_compressor(
     https://numpy.org/doc/2.1/reference/generated/numpy.dtype.kind.html
     """
     dtype = np.dtype(dtype)
-    default_compressors = config.get("v2_default_compressors")
+    default_compressor = config.get("v2_default_compressor")
     if dtype.kind in "biufcmM":
         dtype_key = "numeric"
     elif dtype.kind in "U":
-        dtype_key = "unicode"
+        dtype_key = "string"
     elif dtype.kind in "OSV":
         dtype_key = "bytes"
     else:
         raise ValueError(f"Unsupported dtype kind {dtype.kind}")
 
-    return [{"id": f} for f in default_compressors[dtype_key]], None
+    return [{"id": default_compressor[dtype_key]}], None

tests/test_config.py

@@ -63,10 +63,10 @@ def test_config_defaults_set() -> None:
                 "vlen-utf8": "zarr.codecs.vlen_utf8.VLenUTF8Codec",
                 "vlen-bytes": "zarr.codecs.vlen_utf8.VLenBytesCodec",
             },
-            "v2_default_compressors": {
-                "numeric": ["zstd"],
-                "unicode": ["vlen-utf8"],
-                "bytes": ["vlen-bytes"],
+            "v2_default_compressor": {
+                "numeric": "zstd",
+                "string": "vlen-utf8",
+                "bytes": "vlen-bytes",
             },
         }
     ]

tests/test_v2.py

@@ -84,8 +84,8 @@ def test_codec_pipeline() -> None:
 async def test_v2_encode_decode(dtype):
     with config.set(
         {
-            "v2_default_compressors": {
-                "bytes": ["vlen-bytes"],
+            "v2_default_compressor": {
+                "bytes": "vlen-bytes",
             },
         }
     ):
@@ -126,9 +126,9 @@ def test_v2_encode_decode_with_data(dtype_value):
     dtype, value = dtype_value
     with config.set(
         {
-            "v2_default_compressors": {
-                "unicode": ["vlen-utf8"],
-                "bytes": ["vlen-bytes"],
+            "v2_default_compressor": {
+                "string": "vlen-utf8",
+                "bytes": "vlen-bytes",
             },
         }
     ):
@@ -215,10 +215,10 @@ def test_v2_non_contiguous(array_order: Literal["C", "F"], data_order: Literal["
 def test_default_filters_and_compressor(dtype_expected: Any) -> None:
     with config.set(
         {
-            "v2_dtype_kind_to_default_filters_and_compressor": {
-                "numeric": ["zstd"],
-                "unicode": ["vlen-utf8"],
-                "bytes": ["vlen-bytes"],
+            "v2_default_compressor": {
+                "numeric": "zstd",
+                "string": "vlen-utf8",
+                "bytes": "vlen-bytes",
             },
         }
     ):