mathplotlib imshow复杂的2D数组 [英] mathplotlib imshow complex 2D array

问题描述

有什么好方法可以在mathplotlib中将二维复数数组绘制为图像吗?

Is there any good way how to plot 2D array of complex numbers as image in mathplotlib ?

将复数的大小映射为亮度"或饱和度"，将相位映射为色相"非常有意义(无论如何，色相在RBG颜色空间中不过是相位). http://en.wikipedia.org/wiki/HSL_and_HSV

It makes very much sense to map magnitude of complex number as "brightness" or "saturation" and phase as "Hue" ( anyway Hue is nothing else than phase in RBG color space). http://en.wikipedia.org/wiki/HSL_and_HSV

但是据我所知，imshow确实只接受标量值，然后使用某种色标进行映射.有没有像绘制真实的RGB图片一样的东西?

But as far as I know imshow does accept only scalar values which are then mapped using some colorscale. There is nothing like ploting real RGB pictures?

我觉得只要实现一个接受3个浮点数的元组(向量)的2D数组或形状为[:，:，3]的ndarray的ndarray的版本就容易了.我想这通常是有用的功能.这对于绘制真实的RGB彩色图像(例如从OpenCL输出的纹理)也很有用

I thing it would be easy just implement a version which accepts 2D array of tuples (vectors) of 3 floating point numbers or ndarray of floats of shape [:,:,3]. I guess this would be generally usefful feature. It would be also usefull for plotting real RGB colord images, such as textures outputted from OpenCL

推荐答案

这几乎与@Hooked代码相同，但速度更快.

this does almost the same of @Hooked code but very much faster.

import numpy as np
from numpy import pi
import pylab as plt
from colorsys import hls_to_rgb

def colorize(z):
    r = np.abs(z)
    arg = np.angle(z) 

    h = (arg + pi)  / (2 * pi) + 0.5
    l = 1.0 - 1.0/(1.0 + r**0.3)
    s = 0.8

    c = np.vectorize(hls_to_rgb) (h,l,s) # --> tuple
    c = np.array(c)  # -->  array of (3,n,m) shape, but need (n,m,3)
    c = c.swapaxes(0,2) 
    return c

N=1000
x,y = np.ogrid[-5:5:N*1j, -5:5:N*1j]
z = x + 1j*y

w = 1/(z+1j)**2 + 1/(z-2)**2
img = colorize(w)
plt.imshow(img)
plt.show()

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