有一段时间,我非常烦恼于matplotlib不能生成随机颜色的colormap,因为这是分割和聚类任务中常见的需要。
仅仅生成随机颜色可能会得到一些过于明亮或者过于暗淡的颜色,使得可视化变得困难。此外,通常我们需要第一个或最后一个颜色为黑色,代表背景或离群值。所以我为了我的日常工作编写了一个小函数。
以下是它的行为:
new_cmap = rand_cmap(100, type='bright', first_color_black=True, last_color_black=False, verbose=True)
![生成的颜色地图](https://istack.dev59.com/iZQis.webp)
然后,您只需将 new_cmap 用作matplotlib上的自定义颜色地图:
ax.scatter(X,Y, c=label, cmap=new_cmap, vmin=0, vmax=num_labels)
代码在这里:
def rand_cmap(nlabels, type='bright', first_color_black=True, last_color_black=False, verbose=True):
"""
Creates a random colormap to be used together with matplotlib. Useful for segmentation tasks
:param nlabels: Number of labels (size of colormap)
:param type: 'bright' for strong colors, 'soft' for pastel colors
:param first_color_black: Option to use first color as black, True or False
:param last_color_black: Option to use last color as black, True or False
:param verbose: Prints the number of labels and shows the colormap. True or False
:return: colormap for matplotlib
"""
from matplotlib.colors import LinearSegmentedColormap
import colorsys
import numpy as np
if type not in ('bright', 'soft'):
print ('Please choose "bright" or "soft" for type')
return
if verbose:
print('Number of labels: ' + str(nlabels))
if type == 'bright':
randHSVcolors = [(np.random.uniform(low=0.0, high=1),
np.random.uniform(low=0.2, high=1),
np.random.uniform(low=0.9, high=1)) for i in xrange(nlabels)]
randRGBcolors = []
for HSVcolor in randHSVcolors:
randRGBcolors.append(colorsys.hsv_to_rgb(HSVcolor[0], HSVcolor[1], HSVcolor[2]))
if first_color_black:
randRGBcolors[0] = [0, 0, 0]
if last_color_black:
randRGBcolors[-1] = [0, 0, 0]
random_colormap = LinearSegmentedColormap.from_list('new_map', randRGBcolors, N=nlabels)
if type == 'soft':
low = 0.6
high = 0.95
randRGBcolors = [(np.random.uniform(low=low, high=high),
np.random.uniform(low=low, high=high),
np.random.uniform(low=low, high=high)) for i in xrange(nlabels)]
if first_color_black:
randRGBcolors[0] = [0, 0, 0]
if last_color_black:
randRGBcolors[-1] = [0, 0, 0]
random_colormap = LinearSegmentedColormap.from_list('new_map', randRGBcolors, N=nlabels)
if verbose:
from matplotlib import colors, colorbar
from matplotlib import pyplot as plt
fig, ax = plt.subplots(1, 1, figsize=(15, 0.5))
bounds = np.linspace(0, nlabels, nlabels + 1)
norm = colors.BoundaryNorm(bounds, nlabels)
cb = colorbar.ColorbarBase(ax, cmap=random_colormap, norm=norm, spacing='proportional', ticks=None,
boundaries=bounds, format='%1i', orientation=u'horizontal')
return random_colormap
这个项目也在Github上:
https://github.com/delestro/rand_cmap
distinctify
Python库:https://dev59.com/pHRB5IYBdhLWcg3w6bUD#68414642 - user202729