Matplotlib颜色根据类标签

Question

我有两个向量,一个带有值,另一个带有1,2,3等类标签.

我想将所有属于1级的点用红色绘制,用2级用蓝色绘制,用3级用绿色绘制等等.我该怎么做？

Answer 1

已接受的答案是有效的,但是如果您可能想要指定应将哪个类别标签分配给特定颜色或标签,则可以执行以下操作.我用彩条做了一个小标签体操,但是让情节本身减少到一个漂亮的单线.这非常适合绘制使用sklearn完成的分类的结果.每个标签与(x,y)坐标匹配.

import matplotlib
import matplotlib.pyplot as plt
import numpy as np

x = [4,8,12,16,1,4,9,16]
y = [1,4,9,16,4,8,12,3]
label = [0,1,2,3,0,1,2,3]
colors = ['red','green','blue','purple']

fig = plt.figure(figsize=(8,8))
plt.scatter(x, y, c=label, cmap=matplotlib.colors.ListedColormap(colors))

cb = plt.colorbar()
loc = np.arange(0,max(label),max(label)/float(len(colors)))
cb.set_ticks(loc)
cb.set_ticklabels(colors)

使用此答案的略微修改版本,可以将上述N种颜色概括如下:

import numpy as np
import matplotlib as mpl
import matplotlib.pyplot as plt

N = 23 # Number of labels

# setup the plot
fig, ax = plt.subplots(1,1, figsize=(6,6))
# define the data
x = np.random.rand(1000)
y = np.random.rand(1000)
tag = np.random.randint(0,N,1000) # Tag each point with a corresponding label    

# define the colormap
cmap = plt.cm.jet
# extract all colors from the .jet map
cmaplist = [cmap(i) for i in range(cmap.N)]
# create the new map
cmap = cmap.from_list('Custom cmap', cmaplist, cmap.N)

# define the bins and normalize
bounds = np.linspace(0,N,N+1)
norm = mpl.colors.BoundaryNorm(bounds, cmap.N)

# make the scatter
scat = ax.scatter(x,y,c=tag,s=np.random.randint(100,500,N),cmap=cmap,     norm=norm)
# create the colorbar
cb = plt.colorbar(scat, spacing='proportional',ticks=bounds)
cb.set_label('Custom cbar')
ax.set_title('Discrete color mappings')
plt.show()

这使:

Answer 2

假设您的数据是二维数组,这应该有效:

import numpy
import pylab
xy = numpy.zeros((2, 1000))
xy[0] = range(1000)
xy[1] = range(1000)
colors = [int(i % 23) for i in xy[0]]
pylab.scatter(xy[0], xy[1], c=colors)
pylab.show()

您还可以设置cmap属性以通过使用色彩映射来控制将显示哪些颜色; 即用以下代码替换pylab.scatter:

pylab.scatter(xy[0], xy[1], c=colors, cmap=pylab.cm.cool)

可以在此处找到颜色映射列表

Answer 3

一个简单的解决方案是为每个类指定颜色.这样,我们就可以控制每个类的每种颜色.例如:

arr1 = [1, 2, 3, 4, 5]
arr2 = [2, 3, 3, 4, 4]
labl = [0, 1, 1, 0, 0]
color= ['red' if l == 0 else 'green' for l in labl]
plt.scatter(arr1, arr2, color=color)