python/matplotlib-多色线 [英] python/matplotlib - multicolor line

问题描述

我正在尝试创建具有特定条件的彩色线条.基本上，我想使该线在y轴上指向下时为红色，向上时为绿色，而在两者都不指向时为蓝色.

I am trying to create a colored line with certain conditions. Basically I would like to have the line colored red when pointing down on the y axis, green when pointing up and blue when neither.

我使用了一些类似的示例，但我一直无法将它们转换为与轴上的plot()一起使用.只是想知道如何做到这一点.

I played around with some similar examples I found but I have never been able to convert them to work with plot() on an axis. Just wondering how this could be done.

到目前为止，我想出了一些代码:

Here is some code that I have come up with so far:

#create x,y coordinates
x = numpy.random.choice(10,10)
y = numpy.random.choice(10,10)

#create an array of colors based on direction of line (0=r, 1=g, 2=b)
colors = []
#create an array that is one position away from original 
#to determine direction of line 
yCopy = list(y[1:])
for y1,y2 in zip(y,yCopy):
    if y1 > y2:
        colors.append(0)
    elif y1 < y2:
        colors.append(1)
    else:
        colors.append(2)
#add tenth spot to array as loop only does nine
colors.append(2)

#create a numpy array of colors
categories = numpy.array(colors)

#create a color map with the three colors
colormap = numpy.array([matplotlib.colors.colorConverter.to_rgb('r'),matplotlib.colors.colorConverter.to_rgb('g'),matplotlib.colors.colorConverter.to_rgb('b')])

#plot line
matplotlib.axes.plot(x,y,color=colormap[categories])

不确定如何获取plot()来接受颜色数组.关于用作颜色的格式类型，我总是会出现错误.尝试使用十六进制，十进制，字符串和浮点数.与scatter()完美搭配.

Not sure how to get plot() to accept an array of colors. I always get an error about the format type used as the color. Tried heximal, decimal, string and float. Works perfect with scatter().

谢谢

推荐答案

我认为您不能在plot中使用颜色数组(文档说，颜色可以是任何matlab颜色，而文档说您可以使用数组).

I don't think that you can use an array of colors in plot (the documentation says that color can be any matlab color, while the scatter docs say you can use an array).

但是，您可以通过分别绘制每条线来伪造它:

However, you could fake it by plotting each line separately:

import numpy
from matplotlib import pyplot as plt

x = range(10)
y = numpy.random.choice(10,10)
for x1, x2, y1,y2 in zip(x, x[1:], y, y[1:]):
    if y1 > y2:
        plt.plot([x1, x2], [y1, y2], 'r')
    elif y1 < y2:
        plt.plot([x1, x2], [y1, y2], 'g')
    else:
        plt.plot([x1, x2], [y1, y2], 'b')

plt.show()

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