Add an example of getting a slice out of a C2Array

Author: FrancescAlted

examples/c2array-get-slice.py

@@ -0,0 +1,37 @@
+#######################################################################
+# Copyright (c) 2019-present, Blosc Development Team <[email protected]>
+# All rights reserved.
+#
+# This source code is licensed under a BSD-style license (found in the
+# LICENSE file in the root directory of this source tree)
+#######################################################################
+
+# Example for opening and reading a C2Array (remote array)
+
+from time import time
+
+import numpy as np
+
+import blosc2
+
+urlbase = "https://cat2.cloud/demo"
+root = "@public"
+
+# Access the server
+# urlpath = blosc2.URLPath(f'{root}/examples/ds-1d.b2nd', urlbase)
+# urlpath = blosc2.URLPath(f'{root}/examples/sa-1M.b2nd', urlbase)
+urlpath = blosc2.URLPath(f"{root}/examples/lung-jpeg2000_10x.b2nd", urlbase)
+# urlpath = blosc2.URLPath(f'{root}/examples/uncompressed_lung-jpeg2000_10x.b2nd', urlbase)
+
+# Open the remote array
+t0 = time()
+remote_array = blosc2.open(urlpath, mode="r")
+size = np.prod(remote_array.shape) * remote_array.cparams.typesize
+print(f"Time for opening data (HTTP): {time() - t0:.3f}s - file size: {size / 2**10:.2f} KB")
+
+# Fetch a slice of the remote array as a numpy array
+t0 = time()
+a = remote_array[5:9]
+print(f"Time for reading data (HTTP): {time() - t0:.3f}s - {a.nbytes / 2**10:.2f} KB")
+
+# TODO: Fetch a slice of the remote array as a blosc2.NDArray

src/blosc2/ndarray.py

@@ -1929,7 +1929,7 @@ def slice(self, key: int | slice | Sequence[slice], **kwargs: Any) -> NDArray:
         key, mask = process_key(key, self.shape)
         start, stop, step = get_ndarray_start_stop(self.ndim, key, self.shape)
 
-        # Fast path for slices made with consecutive chunks
+        # Fast path for slices made with aligned chunks
         if step == (1,) * self.ndim:
             aligned_chunks = detect_aligned_chunks(key, self.shape, self.chunks, consecutive=False)
             if aligned_chunks: