Numpy——np.diag()一文看懂

青_丘

于 2022-07-11 13:43:36 发布

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分类专栏： Numpy学习记录文章标签： numpy python 开发语言

本文链接：https://blog.youkuaiyun.com/m0_56316007/article/details/125719529

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这篇博客详细介绍了numpy库中的diag函数，该函数用于从二维数组中提取指定对角线元素，或者根据一维数组构建对角矩阵。通过示例展示了当k值为0、正数和负数时，如何影响对角线的选择。无论v是一维还是二维数组，diag都能灵活处理。文章总结了函数参数和返回值的特点，帮助读者深入理解该函数的用法。

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1.np.diag(v, k): 官方文档如下

@array_function_dispatch(_diag_dispatcher)

def diag(v: Union[ndarray, Iterable, int, float],
k: Optional[int] = 0) -> Any
Extract a diagonal or construct a diagonal array.
See the more detailed documentation for numpy.diagonal if you use this function to extract a diagonal and wish to write to the resulting array; whether it returns a copy or a view depends on what version of numpy you are using.
See Also
diagonal
Return specified diagonals.
diagflat
Create a 2-D array with the flattened input as a diagonal.
trace
Sum along diagonals.
triu
Upper triangle of an array.
tril
Lower triangle of an array.
Examples
>>> x = np.arange(9).reshape((3,3))
>>> x
array([[0, 1, 2],
[3, 4, 5],
[6, 7, 8]])
>>> np.diag(x)
array([0, 4