nlcpy.savetxt(fname, X, fmt='%.18e', delimiter=' ', newline='n', header='', footer='', comments='# ', encoding=None)[ソース]

Saves an array to a text file.

fnamefilename or file handle

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

x1D or 2D array_like

Data to be saved to a text file.

fmtstr 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

delimiterstr, optional

String or character separating columns.

newlinestr, optional

String or character separating lines.

headerstr, optional

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

footerstr, optional

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

commentsstr, 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.

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'.



Saves an array to a binary file in NumPy .npy format.


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


Saves several arrays into a single file in compressed .npz format.


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


- : left justify

+ : Forces to precede result with + or -.

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


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

  • 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.


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 Format Specification Mini-Language, Python Documentation.


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