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基于外部变量的Matplolib行颜色[duplicate]

matplotlib

roberto.sannazzaro · 技术社区 · 7 年前

我用我发现的一些类似的例子进行了尝试,但是我从来没有能够将它们转换为在轴上使用plot()的方法。只是想知道怎么做。

以下是我到目前为止提出的一些代码:

#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])

谢谢

0 回复 | 直到 9 年前

Julien Spronck 9 年前

我不认为你可以在 plot (文档中说颜色可以是任何matlab颜色,而 scatter 医生说你可以使用数组)。

但是,可以通过分别绘制每一行来伪造:

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()

bandito40 9 年前

好啊。所以我想出了如何用LineCollecion在轴上画线。

import numpy as np
import pylab as pl
from matplotlib import collections  as mc

segments = []
colors = np.zeros(shape=(10,4))
x = range(10)
y = np.random.choice(10,10)
i = 0

for x1, x2, y1,y2 in zip(x, x[1:], y, y[1:]):
    if y1 > y2:
        colors[i] = tuple([1,0,0,1])
    elif y1 < y2:
        colors[i] = tuple([0,1,0,1])
    else:
        colors[i] = tuple([0,0,1,1])
    segments.append([(x1, y1), (x2, y2)])
    i += 1     

lc = mc.LineCollection(segments, colors=colors, linewidths=2)
fig, ax = pl.subplots()
ax.add_collection(lc)
ax.autoscale()
ax.margins(0.1)
pl.show()

ImportanceOfBeingErnest 7 年前

有一个 example on the matplotlib page LineCollection 画一条五彩线。

剩下的问题是获取行集合的颜色。所以如果 y

cm = dict(zip(range(-1,2,1),list("gbr")))
colors = list( map( cm.get , np.sign(np.diff(y))  ))

完整代码:

import numpy as np; np.random.seed(5)
import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection

x = np.arange(10)
y = np.random.choice(10,10)

points = np.array([x, y]).T.reshape(-1, 1, 2)
segments = np.concatenate([points[:-1], points[1:]], axis=1)

cm = dict(zip(range(-1,2,1),list("rbg")))
colors = list( map( cm.get , np.sign(np.diff(y))  ))

lc = LineCollection(segments, colors=colors, linewidths=2)
fig, ax = plt.subplots()
ax.add_collection(lc)

ax.autoscale()
ax.margins(0.1)
plt.show()