# numpy.savetxt

numpy.savetxt(fname, X, fmt='%.18e', delimiter=' ', newline='\n', header='', footer='', comments='# ', encoding=None)

  Save an array to a text file.

  Parameters
    fname filename or file handle

      If the filename ends in `.gz`, the file is automatically saved in compressed gzip format. `loadtxt` understands gzipped files transparently.

    X 1D or 2D array_like

      Data to be saved to a text file.

    fmt str or sequence of strs, optional

      A single format (%10.5f), a sequence of formats, or a multi-format string, e.g. ‘Iteration %d – %10.5f’, in which case delimiter is ignored. For complex X, the legal options for fmt are:

      - a single specifier, fmt=’%.4e’, resulting in numbers formatted like ‘ (%s+%sj)’ % (fmt, fmt)

      - a full string specifying every real and imaginary part, e.g. ‘ %.4e %+.4ej %.4e %+.4ej %.4e %+.4ej’ for 3 columns

      - a list of specifiers, one per column - in this case, the real and imaginary part must have separate specifiers, e.g. [‘%.3e + %.3ej’, ‘(%.15e%+.15ej)’] for 2 columns

    delimiter str, optional

      String or character separating columns.

    newline str, optional

      String or character separating lines.

      New in version 1.5.0.

    header str, optional

      String that will be written at the beginning of the file.

      New in version 1.7.0.

    footer str, optional

      String that will be written at the end of the file.

      New in version 1.7.0.

    comments str, optional

      String that will be prepended to the `header` and `footer` strings, to mark them as comments. Default: ‘# ‘, as expected by e.g. `numpy.loadtxt`.

      New in version 1.7.0.

    encoding{None, str}, optional

      Encoding used to encode the outputfile. Does not apply to output streams. If the encoding is something other than ‘bytes’ or ‘latin1’ you will not be able to load the file in NumPy versions < 1.14. Default is ‘latin1’.

      New in version 1.14.0.

  See also

  `save`

    Save an array to a binary file in NumPy `.npy` format

  `savez`

    Save several arrays into an uncompressed `.npz` archive

  `savez_compressed`

    Save several arrays into a compressed `.npz` archive

  Notes

  Further explanation of the fmt parameter (`%[flag]width[.precision]specifier`):

  flags:

    `-` : left justify

    `+` : Forces to precede result with + or -.

    `0` : Left pad the number with zeros instead of space (see width).

  width:

    Minimum number of characters to be printed. The value is not truncated if it has more characters.

  precision:

    - For integer specifiers (eg. `d,i,o,x`), the minimum number of digits.

    - For `e, E` and `f` specifiers, the number of digits to print after the decimal point.

    - For `g` and `G`, the maximum number of significant digits.

    - For `s`, the maximum number of characters.

  specifiers:

    `c` : character

    `d` or `i` : signed decimal integer

    `e` or `E` : scientific notation with `e` or `E`.

    `f` : decimal floating point

    `g,G` : use the shorter of `e,E` or `f`

    `o` : signed octal

    `s` : string of characters

    `u` : unsigned decimal integer

    `x,X` : unsigned hexadecimal integer

  This explanation of `fmt` is not complete, for an exhaustive specification see [1].

  References

  1

    Format Specification Mini-Language, Python Documentation.

  Examples

      >>> x = y = z = np.arange(0.0,5.0,1.0)
      >>> np.savetxt('test.out', x, delimiter=',')   # X is an array
      >>> np.savetxt('test.out', (x,y,z))   # x,y,z equal sized 1D arrays
      >>> np.savetxt('test.out', x, fmt='%1.4e')   # use exponential notation

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