Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/imageio/plugins/npz.py

@@ -0,0 +1,96 @@
+# -*- coding: utf-8 -*-
+# imageio is distributed under the terms of the (new) BSD License.
+
+""" Storage of image data in npz format. Not a great format, but at least
+it supports volumetric data. And its less than 100 lines.
+"""
+
+import numpy as np
+
+from .. import formats
+from ..core import Format
+
+
+class NpzFormat(Format):
+    """ NPZ is a file format by numpy that provides storage of array
+    data using gzip compression. This imageio plugin supports data of any
+    shape, and also supports multiple images per file.
+
+    However, the npz format does not provide streaming; all data is
+    read/written at once. Further, there is no support for meta data.
+
+    Beware that the numpy npz format has a bug on a certain combination
+    of Python 2.7 and numpy, which can cause the resulting files to
+    become unreadable on Python 3. Also, this format is not available
+    on Pypy.
+
+    See the BSDF format for a similar (but more fully featured) format.
+
+    Parameters for reading
+    ----------------------
+    None
+
+    Parameters for saving
+    ---------------------
+    None
+    """
+
+    def _can_read(self, request):
+        # We support any kind of image data
+        return request.extension in self.extensions
+
+    def _can_write(self, request):
+        # We support any kind of image data
+        return request.extension in self.extensions
+
+    # -- reader
+
+    class Reader(Format.Reader):
+        def _open(self):
+            # Load npz file, which provides another file like object
+            self._npz = np.load(self.request.get_file())
+            assert isinstance(self._npz, np.lib.npyio.NpzFile)
+            # Get list of names, ordered by name, but smarter
+            sorter = lambda x: x.split("_")[-1]
+            self._names = sorted(self._npz.files, key=sorter)
+
+        def _close(self):
+            self._npz.close()
+
+        def _get_length(self):
+            return len(self._names)
+
+        def _get_data(self, index):
+            # Get data
+            if index < 0 or index >= len(self._names):
+                raise IndexError("Index out of range while reading from nzp")
+            im = self._npz[self._names[index]]
+            # Return array and empty meta data
+            return im, {}
+
+        def _get_meta_data(self, index):
+            # Get the meta data for the given index
+            raise RuntimeError("The npz format does not support meta data.")
+
+    # -- writer
+
+    class Writer(Format.Writer):
+        def _open(self):
+            # Npz is not such a great format. We cannot stream to the file.
+            # So we remember all images and write them to file at the end.
+            self._images = []
+
+        def _close(self):
+            # Write everything
+            np.savez_compressed(self.request.get_file(), *self._images)
+
+        def _append_data(self, im, meta):
+            self._images.append(im)  # discart meta data
+
+        def set_meta_data(self, meta):
+            raise RuntimeError("The npz format does not support meta data.")
+
+
+# Register
+format = NpzFormat("npz", "Numpy's compressed array format", "npz", "iIvV")
+formats.add_format(format)