numpy.lib.npyio.NpzFile#

class numpy.lib.npyio.NpzFile(fid)[source]#

A dictionary-like object with lazy-loading of files in the zipped archive provided on construction.

NpzFile is used to load files in the NumPy .npz data archive format. Files containing arrays in .npy format are loaded as arrays; other files are returned as bytes.

The arrays and bytes are lazily loaded on either getitem access using obj['key'] or attribute lookup using obj.f.key. Full file names, including the .npy suffix, can also be used for getitem access and membership tests. A list of all file names, with the .npy suffix removed where present, can be obtained with obj.files and the ZipFile object itself using obj.zip.

Parameters:
fidfile, str, or pathlib.Path

The zipped archive to open. This is either a file-like object or a string containing the path to the archive.

own_fidbool, optional

Whether NpzFile should close the file handle. Requires that fid is a file-like object.

Attributes:
fileslist of str

List of all file names in the archive, with the .npy suffix removed where present.

zipZipFile instance

The ZipFile object initialized with the zipped archive.

fBagObj instance

An object on which attribute can be performed as an alternative to getitem access on the NpzFile instance itself.

allow_picklebool, optional

Allow loading pickled data. Default: False

pickle_kwargsdict, optional

Additional keyword arguments to pass on to pickle.load. These are only useful when loading object arrays saved on Python 2.

max_header_sizeint, optional

Maximum allowed size of the header. Large headers may not be safe to load securely and thus require explicitly passing a larger value. See ast.literal_eval for details. This option is ignored when allow_pickle is passed. In that case the file is by definition trusted and the limit is unnecessary.

Methods

close()

Close the file.

get(key[, default])

D.get(k,[,d]) returns D[k] if k in D, else d.

items()

D.items() returns a set-like object providing a view on the items

keys()

D.keys() returns a set-like object providing a view on the keys

values()

D.values() returns a set-like object providing a view on the values

Examples

>>> import numpy as np
>>> from tempfile import TemporaryFile
>>> outfile = TemporaryFile()
>>> x = np.arange(10)
>>> y = np.sin(x)
>>> np.savez(outfile, x=x, y=y)
>>> _ = outfile.seek(0)

>>> npz = np.load(outfile)
>>> isinstance(npz, np.lib.npyio.NpzFile)
True
>>> npz
NpzFile 'object' with keys: x, y
>>> sorted(npz.files)
['x', 'y']
>>> npz['x']  # getitem access
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> npz['x.npy']  # full file name
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> 'x.npy' in npz
True
>>> npz.f.x  # attribute lookup
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
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