add fill_value output to info

Author: d-v-b

changes/xxxx.feature.rst

@@ -0,0 +1 @@
+Adds ``fill_value`` to the list of attributes displayed in the output of the ``AsyncArray.info()`` method.

docs/user-guide/arrays.rst

@@ -183,6 +183,7 @@ which can be used to print useful diagnostics, e.g.::
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.int32
+   Fill value         : 0
    Shape              : (10000, 10000)
    Chunk shape        : (1000, 1000)
    Order              : C
@@ -200,6 +201,7 @@ prints additional diagnostics, e.g.::
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.int32
+   Fill value         : 0
    Shape              : (10000, 10000)
    Chunk shape        : (1000, 1000)
    Order              : C
@@ -209,8 +211,8 @@ prints additional diagnostics, e.g.::
    Serializer         : BytesCodec(endian=<Endian.little: 'little'>)
    Compressors        : (BloscCodec(typesize=4, cname=<BloscCname.zstd: 'zstd'>, clevel=3, shuffle=<BloscShuffle.bitshuffle: 'bitshuffle'>, blocksize=0),)
    No. bytes          : 400000000 (381.5M)
-   No. bytes stored   : 3558573
-   Storage ratio      : 112.4
+   No. bytes stored   : 9696520
+   Storage ratio      : 41.3
    Chunks Initialized : 100
 
 .. note::
@@ -287,6 +289,7 @@ Here is an example using a delta filter with the Blosc compressor::
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.int32
+   Fill value         : 0
    Shape              : (10000, 10000)
    Chunk shape        : (1000, 1000)
    Order              : C
@@ -601,6 +604,7 @@ Sharded arrays can be created by providing the ``shards`` parameter to :func:`za
   Type               : Array
   Zarr format        : 3
   Data type          : DataType.uint8
+  Fill value         : 0
   Shape              : (10000, 10000)
   Shard shape        : (1000, 1000)
   Chunk shape        : (100, 100)

docs/user-guide/groups.rst

@@ -129,6 +129,7 @@ property. E.g.::
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.int64
+   Fill value         : 0
    Shape              : (1000000,)
    Chunk shape        : (100000,)
    Order              : C
@@ -145,6 +146,7 @@ property. E.g.::
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.float32
+   Fill value         : 0.0
    Shape              : (1000, 1000)
    Chunk shape        : (100, 100)
    Order              : C

docs/user-guide/performance.rst

@@ -92,6 +92,7 @@ To use sharding, you need to specify the ``shards`` parameter when creating the
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.uint8
+   Fill value         : 0
    Shape              : (10000, 10000, 1000)
    Shard shape        : (1000, 1000, 1000)
    Chunk shape        : (100, 100, 100)
@@ -122,6 +123,7 @@ ratios, depending on the correlation structure within the data. E.g.::
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.int32
+   Fill value         : 0
    Shape              : (10000, 10000)
    Chunk shape        : (1000, 1000)
    Order              : C
@@ -141,6 +143,7 @@ ratios, depending on the correlation structure within the data. E.g.::
    Type               : Array
    Zarr format        : 3
    Data type          : DataType.int32
+   Fill value         : 0
    Shape              : (10000, 10000)
    Chunk shape        : (1000, 1000)
    Order              : F

src/zarr/core/_info.py

@@ -67,7 +67,7 @@ def byte_info(size: int) -> str:
         return f"{size} ({human_readable_size(size)})"
 
 
-@dataclasses.dataclass(kw_only=True)
+@dataclasses.dataclass(kw_only=True, frozen=True, slots=True)
 class ArrayInfo:
     """
     Visual summary for an Array.
@@ -79,6 +79,7 @@ class ArrayInfo:
     _type: Literal["Array"] = "Array"
     _zarr_format: ZarrFormat
     _data_type: np.dtype[Any] | DataType
+    _fill_value: object
     _shape: tuple[int, ...]
     _shard_shape: tuple[int, ...] | None = None
     _chunk_shape: tuple[int, ...] | None = None
@@ -97,6 +98,7 @@ def __repr__(self) -> str:
         Type               : {_type}
         Zarr format        : {_zarr_format}
         Data type          : {_data_type}
+        Fill value         : {_fill_value}
         Shape              : {_shape}""")
 
         if self._shard_shape is not None:

src/zarr/core/array.py

@@ -1702,6 +1702,7 @@ def _info(
         return ArrayInfo(
             _zarr_format=self.metadata.zarr_format,
             _data_type=_data_type,
+            _fill_value=self.metadata.fill_value,
             _shape=self.shape,
             _order=self.order,
             _shard_shape=self.shards,