从3D numpy数组创建3D图 [英] Creating a 3D plot from a 3D numpy array

问题描述

好的，所以我觉得应该有一种简单的方法来使用matplotlib创建三维散点图.我有一个3D numpy数组(dset)，其中0是我不想要的点，而1是我想要的点，基本上要绘制它，现在我必须逐步执行以下三个for:循环:

Ok, so I feel like there should be an easy way to create a 3-dimensional scatter plot using matplotlib. I have a 3D numpy array (dset) with 0's where I don't want a point and 1's where I do, basically to plot it now I have to step through three for: loops as such:

for i in range(30):
    for x in range(60):
        for y in range(60):
            if dset[i, x, y] == 1:
                ax.scatter(x, y, -i, zdir='z', c= 'red')

关于如何更有效地完成此工作的任何建议?任何想法将不胜感激.

Any suggestions on how I could accomplish this more efficiently? Any ideas would be greatly appreciated.

推荐答案

如果您具有这样的dset，并且只想获取1值，则可以使用nonzero，它返回一个数组的元组，每个维度对应a，其中包含该维度中非零元素的索引.".

If you have a dset like that, and you want to just get the 1 values, you could use nonzero, which "returns a tuple of arrays, one for each dimension of a, containing the indices of the non-zero elements in that dimension.".

例如，我们可以制作一个简单的3d数组:

For example, we can make a simple 3d array:

>>> import numpy
>>> numpy.random.seed(29)
>>> d = numpy.random.randint(0, 2, size=(3,3,3))
>>> d
array([[[1, 1, 0],
        [1, 0, 0],
        [0, 1, 1]],

       [[0, 1, 1],
        [1, 0, 0],
        [0, 1, 1]],

       [[1, 1, 0],
        [0, 1, 0],
        [0, 0, 1]]])

并找到非零元素的位置:

and find where the nonzero elements are located:

>>> d.nonzero()
(array([0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2]), array([0, 0, 1, 2, 2, 0, 0, 1, 2, 2, 0, 0, 1, 2]), array([0, 1, 0, 1, 2, 1, 2, 0, 1, 2, 0, 1, 1, 2]))
>>> z,x,y = d.nonzero()

如果我们想要更复杂的切割，我们可以做类似(d > 3.4).nonzero()之类的事情，因为True的整数值为1，并且算作非零.

If we wanted a more complicated cut, we could have done something like (d > 3.4).nonzero() or something, as True has an integer value of 1 and counts as nonzero.

最后，我们绘制:

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.scatter(x, y, -z, zdir='z', c= 'red')
plt.savefig("demo.png")

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