如何在ndarray中创建一个球体? [英] How to create a sphere inside an ndarray?

问题描述

我有一个大小为32x32x32的ndarray.我想在数组内部创建一个球体，其中心为(x,y)，半径为4个像素.球形的值为1，而数组的值为0.如何在python中完成?

I have a ndarray of size 32x32x32. I want to create a sphere inside the array with the center at (x,y) and a radius of 4 pixels. The value of the sphere is 1 while value of the array is 0. How can this be done in python?

这是生成数组的代码:

import numpy as np
A = np.zeros((32,32,32))
print (A)

推荐答案

很好的问题.您可以尝试以下代码.在下面提到的代码中，AA是您想要的矩阵. =)

Very good question. You can try the following code. In the below mentioned code AA is the matrix that you want. =)

import numpy as np
from copy import deepcopy

''' size : size of original 3D numpy matrix A.
    radius : radius of circle inside A which will be filled with ones. 
'''
size, radius = 5, 2

''' A : numpy.ndarray of shape size*size*size. '''
A = np.zeros((size,size, size)) 

''' AA : copy of A (you don't want the original copy of A to be overwritten.) '''
AA = deepcopy(A) 

''' (x0, y0, z0) : coordinates of center of circle inside A. '''
x0, y0, z0 = int(np.floor(A.shape[0]/2)), \
        int(np.floor(A.shape[1]/2)), int(np.floor(A.shape[2]/2))


for x in range(x0-radius, x0+radius+1):
    for y in range(y0-radius, y0+radius+1):
        for z in range(z0-radius, z0+radius+1):
            ''' deb: measures how far a coordinate in A is far from the center. 
                    deb>=0: inside the sphere.
                    deb<0: outside the sphere.'''   
            deb = radius - abs(x0-x) - abs(y0-y) - abs(z0-z) 
            if (deb)>=0: AA[x,y,z] = 1

以下是size=5和radius=2(在形状为5*5*5的numpy数组内半径为2像素的球体)的输出示例:

Following is an example of the output for size=5 and radius=2 (a sphere of radius 2 pixels inside a numpy array of shape 5*5*5):

[[[0. 0. 0. 0. 0.]
  [0. 0. 0. 0. 0.]
  [0. 0. 1. 0. 0.]
  [0. 0. 0. 0. 0.]
  [0. 0. 0. 0. 0.]]

 [[0. 0. 0. 0. 0.]
  [0. 0. 1. 0. 0.]
  [0. 1. 1. 1. 0.]
  [0. 0. 1. 0. 0.]
  [0. 0. 0. 0. 0.]]

 [[0. 0. 1. 0. 0.]
  [0. 1. 1. 1. 0.]
  [1. 1. 1. 1. 1.]
  [0. 1. 1. 1. 0.]
  [0. 0. 1. 0. 0.]]

 [[0. 0. 0. 0. 0.]
  [0. 0. 1. 0. 0.]
  [0. 1. 1. 1. 0.]
  [0. 0. 1. 0. 0.]
  [0. 0. 0. 0. 0.]]

 [[0. 0. 0. 0. 0.]
  [0. 0. 0. 0. 0.]
  [0. 0. 1. 0. 0.]
  [0. 0. 0. 0. 0.]
  [0. 0. 0. 0. 0.]]]

我没有按照要求的尺寸和半径(size=32和radius=4)打印输出，因为输出会很长.

I haven't printed the output for the size and radius that you had asked for (size=32 and radius=4), as the output will be very long.

这篇关于如何在ndarray中创建一个球体?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！