This is documentation for an old release of NumPy (version 1.18). Read this page Search for this page in the documentation of the latest stable release (version 2.2).

Input and output

NumPy binary files (NPY, NPZ)

load(file[, mmap_mode, allow_pickle, …])	Load arrays or pickled objects from .npy, .npz or pickled files.
save(file, arr[, allow_pickle, fix_imports])	Save an array to a binary file in NumPy .npy format.
savez(file, \*args, \*\*kwds)	Save several arrays into a single file in uncompressed .npz format.
savez_compressed(file, \*args, \*\*kwds)	Save several arrays into a single file in compressed .npz format.

The format of these binary file types is documented in numpy.lib.format

Text files

loadtxt(fname[, dtype, comments, delimiter, …])	Load data from a text file.
savetxt(fname, X[, fmt, delimiter, newline, …])	Save an array to a text file.
genfromtxt(fname[, dtype, comments, …])	Load data from a text file, with missing values handled as specified.
fromregex(file, regexp, dtype[, encoding])	Construct an array from a text file, using regular expression parsing.
fromstring(string[, dtype, count, sep])	A new 1-D array initialized from text data in a string.
ndarray.tofile(fid[, sep, format])	Write array to a file as text or binary (default).
ndarray.tolist()	Return the array as an a.ndim-levels deep nested list of Python scalars.

Raw binary files

fromfile(file[, dtype, count, sep, offset])	Construct an array from data in a text or binary file.
ndarray.tofile(fid[, sep, format])	Write array to a file as text or binary (default).

String formatting

array2string(a[, max_line_width, precision, …])	Return a string representation of an array.
array_repr(arr[, max_line_width, precision, …])	Return the string representation of an array.
array_str(a[, max_line_width, precision, …])	Return a string representation of the data in an array.
format_float_positional(x[, precision, …])	Format a floating-point scalar as a decimal string in positional notation.
format_float_scientific(x[, precision, …])	Format a floating-point scalar as a decimal string in scientific notation.

Memory mapping files

memmap

Create a memory-map to an array stored in a binary file on disk.

Text formatting options

set_printoptions([precision, threshold, …])	Set printing options.
get_printoptions()	Return the current print options.
set_string_function(f[, repr])	Set a Python function to be used when pretty printing arrays.
printoptions(\*args, \*\*kwargs)	Context manager for setting print options.

Base-n representations

binary_repr(num[, width])	Return the binary representation of the input number as a string.
base_repr(number[, base, padding])	Return a string representation of a number in the given base system.

Data sources

DataSource([destpath])

A generic data source file (file, http, ftp, …).

Binary Format Description

lib.format

Binary serialization