python - Seaborn 调色板 - 防止颜色回收

Question

Seaborn 允许定义包含多种颜色的调色板，这对于具有多条线的图表很有用。但是，将调色板设置为具有多种颜色的调色板时，仅使用前六种颜色，之后颜色会循环使用，从而难以区分线条。这可以通过显式调用调色板来覆盖，但这并不方便。当定义超过 6 个颜色时，有没有办法强制 Seaborn 当前调色板不回收颜色？

例子：

from matplotlib import pyplot as plt
import pandas as pd
import seaborn as sb

# Define a palette with 8 colors
cmap = sb.blend_palette(["firebrick", "palegreen"], 8) 
sb.palplot(cmap)

# Set the current palette to this; only 6 colors are used
sb.set_palette(cmap)
sb.palplot(sb.color_palette() )

df = pd.DataFrame({x:[x*10, x*10+5, x*10+10] for x in range(8)})
fig, (ax1, ax2) = plt.subplots(2,1,figsize=(4,6))
# Using the current palette, colors repeat 
df.plot(ax=ax1) 
ax1.legend(bbox_to_anchor=(1.2, 1)) 
# using the palette that defined the current palette, colors don't repeat
df.plot(ax=ax2, color=cmap) 
ax2.legend(bbox_to_anchor=(1.2, 1))  ;

Answer 1

解决方案（感谢@tcaswell 提供的指针）：使用所有颜色显式设置调色板：

# Setting the palette using defaults only finds 6 colors
sb.set_palette(cmap)
sb.palplot(sb.color_palette() )
sb.palplot(sb.color_palette(n_colors=8) )

# but setting the number of colors explicitly allows it to use them all
sb.set_palette(cmap, n_colors=8)
# Even though unless you explicitly request all the colors it only shows 6
sb.palplot(sb.color_palette() )
sb.palplot(sb.color_palette(n_colors=8) )

# In a chart, the palette now has access to all 8 
fig, ax1 = plt.subplots(1,1,figsize=(4,3)) 
df.plot(ax=ax1) 
ax1.legend(bbox_to_anchor=(1.2, 1)) ;