Python Numpy-将非常小的数字视为零 [英] Python Numpy - Treat really small numbers as zero

问题描述

我想用Numpy计算奇异矩阵的行列式(行列式为0)，当我打印行列式时，行列式显示的数字非常小(几乎为零= -7.09974814699e-30)，但自身不为零...

I want to calculate the Determinant of a Singular Matrix (which has a 0 determinant) with Numpy and when I print the determinant it shows a really small number (which is nearly zero = -7.09974814699e-30) but not zero itself...

当我尝试使用％s，％d或％f打印行列式时，有时为零，有时为-0，有时为-7.09974814699e-30.

when I try to print the determinant either with %s, %d or %f, sometimes it's zero, sometimes -0 and sometimes -7.09974814699e-30 .

这是代码:

import numpy as np

array = np.arange(16)
array = array.reshape(4, -1)
determinant = np.linalg.det(array)

print("Determinant is %s" % determinant)
print("Determinant is %d" % determinant)
print("Determinant is %f" % determinant)

Determinant is -7.09974814699e-30
Determinant is 0
Determinant is -0.000000

我如何使Numpy将非常小的数字(例如-7.09974814699e-30)视为零并向我显示零.我还问过这个问题，如果您看一下矩阵，看到它充满了很小的数字，但不是零，它应该是一个对角矩阵，对角线上有数字，而其他地方为零...

How can I make Numpy treat really small numbers such as -7.09974814699e-30 as zero and show zero to me. I also asked this question before, if you take a look at the matrix you see that it's filled with really small numbers but not zero while it should be a diagonal matrix with numbers on the diagonal and zeros elsewhere...

谢谢...

推荐答案

>>> if np.abs(determinant) < 0.000001:
...     determinant=0
...
>>> print determinant
0

对于数组，您可以使用单个操作来完成(请参见我对其他问题的回答: https://stackoverflow. com/a/36395905/5088142 )

In case of array you can do it using a single operation (see my answer to your other question: https://stackoverflow.com/a/36395905/5088142)

要将小于eps的数组元素设置为零:

To set array elements that are less than eps to zero:

array[np.abs(array) < eps] = 0

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