numpy.savez#
- numpy.savez(file, *args, **kwds)[source]#
Save several arrays into a single file in uncompressed
.npz
format.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 arr_0, arr_1, etc.- Parameters:
- filefile, str, or pathlib.Path
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.- argsArguments, optional
Arrays to save to the file. Please use keyword arguments (see kwds below) to assign names to arrays. Arrays specified as args will be named “arr_0”, “arr_1”, and so on.
- kwdsKeyword arguments, optional
Arrays to save to the file. Each array will be saved to the output file with its corresponding keyword name.
- Returns:
- None
See also
save
Save a single array to a binary file in NumPy format.
savetxt
Save an array to a file as plain text.
savez_compressed
Save several arrays into a compressed
.npz
archive
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, seenumpy.lib.format
.When opening the saved
.npz
file withload
aNpzFile
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 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 thefile
argument to be defined twice in the call tosavez
.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 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])