Return ndarrays from decode where possible

Where possible, ensure that `decode` returns an `ndarray`. Many codecs
already do this except for some unusual ones that work with Python
objects or text data. In the cases where the data is known to be binary,
try to return `ndarray`s. This makes it pretty easy for end users of
this data to do whatever they would like with it.

Author: jakirkham

numcodecs/blosc.pyx

@@ -493,7 +493,8 @@ class Blosc(Codec):
 
     def decode(self, buf, out=None):
         buf = ensure_contiguous_ndarray(buf, self.max_buffer_size)
-        return decompress(buf, out)
+        out = decompress(buf, out)
+        return ensure_ndarray(out)
 
     def __repr__(self):
         r = '%s(cname=%r, clevel=%r, shuffle=%s, blocksize=%s)' % \

numcodecs/lz4.pyx

@@ -223,7 +223,7 @@ class LZ4(Codec):
 
     def decode(self, buf, out=None):
         buf = ensure_contiguous_ndarray(buf, self.max_buffer_size)
-        return decompress(buf, out)
+        return ensure_ndarray(decompress(buf, out))
 
     def __repr__(self):
         r = '%s(acceleration=%r)' % \

numcodecs/zstd.pyx

@@ -218,7 +218,7 @@ class Zstd(Codec):
 
     def decode(self, buf, out=None):
         buf = ensure_contiguous_ndarray(buf)
-        return decompress(buf, out)
+        return ensure_ndarray(decompress(buf, out))
 
     def __repr__(self):
         r = '%s(level=%r)' % \