将整数值的范围映射到python中的颜色

Question

我的整数范围从0到10000.我想将颜色映射到每个。然后基于整数值我想要检索RGB等效于整数值的颜色。基本上我想要在两种或更多种颜色之间具有插值效果，例如如果颜色是绿色和红色，则绿色具有最小重量（0），红色具有最高重量（10000）。我如何使用matplotlib实现此映射，或者是否有任何其他库。

Answer 1

确实可以从给定的色彩图中采样10000种颜色：

#!/usr/bin/python3

from numpy import arange

from matplotlib import pyplot as plt
from matplotlib import cm
from matplotlib.colors import LinearSegmentedColormap


# ======
## data:

N = 10000
data = arange(N +1)


# =================
## custom colormap:

# red-green colormap:
cdict = {'red':   [(0.0, 1.0, 1.0),  # red decreases
                   (1.0, 0.0, 0.0)],

         'green': [(0.0, 0.0, 0.0),  # green increases
                   (1.0, 1.0, 1.0)],

         'blue':  [(0.0, 0.0, 0.0),  # no blue at all
                   (1.0, 0.0, 0.0)]}

red_green_cm = LinearSegmentedColormap('RedGreen', cdict, N)


# ======
## plot:

colors = cm.get_cmap(red_green_cm, N)

fig = plt.figure()
ax = fig.add_subplot(111)

# each line is of its own color:
for i, x in enumerate(data):
    ax.plot(data, data*x, color=colors(i))

fig.savefig("red-green-cm.png")

结果：

修改

还可以添加颜色栏：

#!/usr/bin/python3

from numpy import arange

import matplotlib as mpl
from matplotlib import pyplot as plt
from matplotlib import cm
from matplotlib.colors import LinearSegmentedColormap


# ======
## data:

N = 10000
data = arange(N +1)


# =================
## custom colormap:

# red-green colormap:
cdict = {'red':   [(0.0, 1.0, 1.0),  # red decreases
                   (1.0, 0.0, 0.0)],

         'green': [(0.0, 0.0, 0.0),  # green increases
                   (1.0, 1.0, 1.0)],

         'blue':  [(0.0, 0.0, 0.0),  # no blue at all
                   (1.0, 0.0, 0.0)] }

red_green_cm = LinearSegmentedColormap('RedGreen', cdict, N)


# ======
## plot:

colors = cm.get_cmap(red_green_cm, N)

fig = plt.figure()
ax = fig.add_subplot(111)

# each line is of its own color:
for i, x in enumerate(data):
    ax.plot(data, data*x, color=colors(i))

# make space for colorbar:
fig.tight_layout(rect=[0, 0, 0.85, 1])

# adding colorbar:
ax_cb = fig.add_axes([0.85, 0.10, 0.05, 0.8])
norm = mpl.colors.Normalize(vmin=data[0], vmax=data[-1])
cb = mpl.colorbar.ColorbarBase(ax_cb, cmap=red_green_cm, norm=norm, orientation='vertical')

fig.savefig("red-green-cm.png")

Answer 2

范围介于两个极端之间的色彩映射称为Diverging，matplotlib中的RdYlGn（红 - 黄 - 绿）色彩映射完全符合您的要求。看看colormaps reference。我不知道范围是0到10,000，虽然它肯定会处理0到100，你可以将你的范围映射到它。