numpy.ones(shape, dtype=None, order='C', *, device=None, like=None)[source]#

Return a new array of given shape and type, filled with ones.

shapeint or sequence of ints

Shape of the new array, e.g., (2, 3) or 2.

dtypedata-type, optional

The desired data-type for the array, e.g., numpy.int8. Default is numpy.float64.

order{‘C’, ‘F’}, optional, default: C

Whether to store multi-dimensional data in row-major (C-style) or column-major (Fortran-style) order in memory.

devicestr, optional

The device on which to place the created array. Default: None. For Array-API interoperability only, so must be "cpu" if passed.

New in version 2.0.0.

likearray_like, optional

Reference object to allow the creation of arrays which are not NumPy arrays. If an array-like passed in as like supports the __array_function__ protocol, the result will be defined by it. In this case, it ensures the creation of an array object compatible with that passed in via this argument.

New in version 1.20.0.


Array of ones with the given shape, dtype, and order.

See also


Return an array of ones with shape and type of input.


Return a new uninitialized array.


Return a new array setting values to zero.


Return a new array of given shape filled with value.


>>> np.ones(5)
array([1., 1., 1., 1., 1.])
>>> np.ones((5,), dtype=int)
array([1, 1, 1, 1, 1])
>>> np.ones((2, 1))
>>> s = (2,2)
>>> np.ones(s)
array([[1.,  1.],
       [1.,  1.]])