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