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savez(file, *args, **kwds)

Provide arrays as keyword arguments to store them under the corresponding name in the output file: savez(fn, x=x, y=y) .

If arrays are specified as positional arguments, i.e., savez(fn, x, y) , their names will be :None:None:`arr_0`, :None:None:`arr_1`, etc.

Notes

The .npz file format is a zipped archive of files named after the variables they contain. The archive is not compressed and each file in the archive contains one variable in .npy format. For a description of the .npy format, see numpy.lib.format .

When opening the saved .npz file with load a NpzFile object is returned. This is a dictionary-like object which can be queried for its list of arrays (with the .files attribute), and for the arrays themselves.

Keys passed in :None:None:`kwds` are used as filenames inside the ZIP archive. Therefore, keys should be valid filenames; e.g., avoid keys that begin with / or contain . .

When naming variables with keyword arguments, it is not possible to name a variable file , as this would cause the file argument to be defined twice in the call to savez .

Parameters

file : str or file: Either the filename (string) or an open file (file-like object) where the data will be saved. If file is a string or a Path, the .npz extension will be appended to the filename if it is not already there.
args : Arguments, optional: Arrays to save to the file. Please use keyword arguments (see :None:None:`kwds` below) to assign names to arrays. Arrays specified as args will be named "arr_0", "arr_1", and so on.
kwds : Keyword arguments, optional: Arrays to save to the file. Each array will be saved to the output file with its corresponding keyword name.

Returns

None

Save several arrays into a single file in uncompressed .npz format.

Examples

>>> from tempfile import TemporaryFile
... outfile = TemporaryFile()
... x = np.arange(10)
... y = np.sin(x)

Using savez with \*args, the arrays are saved with default names.

>>> np.savez(outfile, x, y)
... _ = outfile.seek(0) # Only needed here to simulate closing & reopening file
... npzfile = np.load(outfile)
... npzfile.files
['arr_0', 'arr_1']

>>> npzfile['arr_0']
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

Using savez with \**kwds, the arrays are saved with the keyword names.

>>> outfile = TemporaryFile()
... np.savez(outfile, x=x, y=y)
... _ = outfile.seek(0)
... npzfile = np.load(outfile)
... sorted(npzfile.files)
['x', 'y']

>>> npzfile['x']
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

numpy.savez_compressed numpy.savetxt numpy.load scipy.sparse._matrix_io.save_npz numpy.savez numpy.save

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