numpy.ones

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

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

Parameters:

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.

在 2.0.0 版本加入.

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.

在 1.20.0 版本加入.

Returns:

outndarray

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

参见

ones_like

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

empty

Return a new uninitialized array.

zeros

Return a new array setting values to zero.

full

Return a new array of given shape filled with value.

Examples

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>>> import numpy as np
>>> np.ones(5)
array([1., 1., 1., 1., 1.])

>>> np.ones((5,), dtype=np.int_)
array([1, 1, 1, 1, 1])

>>> np.ones((2, 1))
array([[1.],
       [1.]])

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

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