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# numpy.savez

`numpy.``savez`(file, *args, **kwds)

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

  If arguments are passed in with no keywords, the corresponding variable names, in the .npz file, are ‘arr_0’, ‘arr_1’, etc. If keyword arguments are given, the corresponding variable names, in the `.npz` file will match the keyword names.

  Parameters : | file : str or file Either the file name (string) or an open file (file-like object) where the data will be saved. If file is a string, the `.npz` extension will be appended to the file name if it is not already there. args : Arguments, optional Arrays to save to the file. Since it is not possible for Python to know the names of the arrays outside `savez`, the arrays will be saved with names “arr_0”, “arr_1”, and so on. These arguments can be any expression. kwds : Keyword arguments, optional Arrays to save to the file. Arrays will be saved in the file with the keyword names.
  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 file format

  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 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.

  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_1', 'arr_0']
      >>> 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)
      >>> npzfile.files
      ['y', 'x']
      >>> npzfile['x']
      array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

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