Test and fix for bytes fill value bug

docs/tutorial.rst

@@ -462,7 +462,7 @@ Diagnostic information about arrays and groups is available via the ``info`` pro
     Compressor         : Blosc(cname='lz4', clevel=5, shuffle=SHUFFLE, blocksize=0)
     Store type         : zarr.storage.DictStore
     No. bytes          : 8000000 (7.6M)
-    No. bytes stored   : 38482 (37.6K)
+    No. bytes stored   : 38484 (37.6K)
     Storage ratio      : 207.9
     Chunks initialized : 10/10
 

zarr/creation.py

@@ -100,9 +100,13 @@ def create(shape, chunks=None, dtype=None, compressor='default',
     # handle polymorphic store arg
     store = _handle_store_arg(store)
 
-    # compatibility
+    # API compatibility with h5py
     compressor, fill_value = _handle_kwargs(compressor, fill_value, kwargs)
 
+    # ensure fill_value of correct type
+    if fill_value is not None:
+        fill_value = np.array(fill_value, dtype=dtype)[()]
+
     # initialize array metadata
     init_array(store, shape=shape, chunks=chunks, dtype=dtype,
                compressor=compressor, fill_value=fill_value, order=order,
@@ -401,9 +405,13 @@ def open_array(store=None, mode='a', shape=None, chunks=None, dtype=None,
     store = _handle_store_arg(store)
     path = normalize_storage_path(path)
 
-    # compatibility
+    # API compatibility with h5py
     compressor, fill_value = _handle_kwargs(compressor, fill_value, kwargs)
 
+    # ensure fill_value of correct type
+    if fill_value is not None:
+        fill_value = np.array(fill_value, dtype=dtype)[()]
+
     # ensure store is initialized
 
     if mode in ['r', 'r+']:

zarr/meta.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import, print_function, division
 import json
+import base64
 
 
 import numpy as np
@@ -40,13 +41,14 @@ def decode_array_metadata(s):
 
 
 def encode_array_metadata(meta):
+    dtype = meta['dtype']
     meta = dict(
         zarr_format=ZARR_FORMAT,
         shape=meta['shape'],
         chunks=meta['chunks'],
-        dtype=encode_dtype(meta['dtype']),
+        dtype=encode_dtype(dtype),
         compressor=meta['compressor'],
-        fill_value=encode_fill_value(meta['fill_value']),
+        fill_value=encode_fill_value(meta['fill_value'], dtype),
         order=meta['order'],
         filters=meta['filters'],
     )
@@ -110,6 +112,9 @@ def encode_group_metadata(meta=None):
 
 
 def decode_fill_value(v, dtype):
+    # early out
+    if v is None:
+        return v
     if dtype.kind == 'f':
         if v == 'NaN':
             return np.nan
@@ -118,20 +123,39 @@ def decode_fill_value(v, dtype):
         elif v == '-Infinity':
             return np.NINF
         else:
+            return np.array(v, dtype=dtype)[()]
+    elif dtype.kind == 'S':
+        try:
+            return base64.standard_b64decode(v)
+        except Exception:
+            # be lenient, allow for other values that may have been used before base64 encoding
+            # and may work as fill values, e.g., the number 0
             return v
     else:
         return v
 
 
-def encode_fill_value(v):
-    try:
+def encode_fill_value(v, dtype):
+    # early out
+    if v is None:
+        return v
+    if dtype.kind == 'f':
         if np.isnan(v):
             return 'NaN'
         elif np.isposinf(v):
             return 'Infinity'
         elif np.isneginf(v):
             return '-Infinity'
         else:
-            return v
-    except TypeError:
+            return float(v)
+    elif dtype.kind in 'ui':
+        return int(v)
+    elif dtype.kind == 'b':
+        return bool(v)
+    elif dtype.kind == 'S':
+        v = base64.standard_b64encode(v)
+        if not PY2:
+            v = str(v, 'ascii')
+        return v
+    else:
         return v

zarr/tests/test_meta.py

@@ -1,13 +1,14 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import, print_function, division
 import json
+import base64
 
 
 from nose.tools import eq_ as eq, assert_is_none, assert_raises
 import numpy as np
 
 
-from zarr.compat import binary_type, text_type
+from zarr.compat import binary_type, text_type, PY2
 from zarr.meta import decode_array_metadata, encode_dtype, decode_dtype, \
     ZARR_FORMAT, decode_group_metadata, encode_array_metadata
 from zarr.errors import MetadataError
@@ -113,7 +114,7 @@ def test_encode_decode_array_2():
     eq([df.get_config()], meta_dec['filters'])
 
 
-def test_encode_decode_array_fill_values():
+def test_encode_decode_fill_values_nan():
 
     fills = (
         (np.nan, "NaN", np.isnan),
@@ -154,6 +155,47 @@ def test_encode_decode_array_fill_values():
         assert f(actual)
 
 
+def test_encode_decode_fill_values_bytes():
+
+    fills = b'foo', bytes(10)
+
+    for v in fills:
+
+        s = base64.standard_b64encode(v)
+        if not PY2:
+            s = str(s, 'ascii')
+
+        meta = dict(
+            shape=(100,),
+            chunks=(10,),
+            dtype=np.dtype('S10'),
+            compressor=Zlib(1).get_config(),
+            fill_value=v,
+            filters=None,
+            order='C'
+        )
+
+        meta_json = '''{
+            "chunks": [10],
+            "compressor": {"id": "zlib", "level": 1},
+            "dtype": "|S10",
+            "fill_value": "%s",
+            "filters": null,
+            "order": "C",
+            "shape": [100],
+            "zarr_format": %s
+        }''' % (s, ZARR_FORMAT)
+
+        # test encoding
+        meta_enc = encode_array_metadata(meta)
+        assert_json_eq(meta_json, meta_enc)
+
+        # test decoding
+        meta_dec = decode_array_metadata(meta_enc)
+        actual = meta_dec['fill_value']
+        eq(v, actual)
+
+
 def test_decode_array_unsupported_format():
 
     # unsupported format