如何修改legend（图例）的文本颜色，使图例文字与对应线条颜色一致？

Python Matplotlib 场景 #

折线/线条类图形 #

• 先正常绘制图形，获取生成的图例对象
• 遍历图例的线条样本和对应文本，同步颜色设置
  示例代码：

import matplotlib.pyplot as plt

# 基础绘图逻辑
fig, ax = plt.subplots()
line1, = ax.plot([1,2,3], [4,5,1], color='#e63946', label='曲线A')
line2, = ax.plot([1,2,3], [2,3,4], color='#1d3557', label='曲线B')
line3, = ax.plot([1,2,3], [3,1,2], color='#457b9d', label='曲线C')

# 获取图例对象
leg = ax.legend()

# 同步文字与线条颜色
for line, text in zip(leg.get_lines(), leg.get_texts()):
    text.set_color(line.get_color())

plt.show()

柱状/填充类图形 #

填充类图形的图例样本存储在get_patches()方法返回的列表中，替换对应方法即可：

import matplotlib.pyplot as plt
import numpy as np

x = np.arange(3)
y1 = [2,5,3]
y2 = [3,4,2]

fig, ax = plt.subplots()
ax.bar(x, y1, color='#fca311', label='柱组A')
ax.bar(x, y2, bottom=y1, color='#14213d', label='柱组B')

leg = ax.legend()
for patch, text in zip(leg.get_patches(), leg.get_texts()):
    text.set_color(patch.get_facecolor())

plt.show()

Python Seaborn 场景 #

Seaborn基于Matplotlib封装，逻辑完全通用，只需拿到绘图返回的坐标轴对象的legend_属性即可：

import seaborn as sns
import matplotlib.pyplot as plt

# 内置示例数据集
tips = sns.load_dataset("tips")
ax = sns.lineplot(data=tips, x="day", y="total_bill", hue="sex")

# 同步颜色
leg = ax.legend_
for line, text in zip(leg.get_lines(), leg.get_texts()):
    text.set_color(line.get_color())

plt.show()

R ggplot2 场景 #

借助ggtext包的富文本渲染能力即可实现，示例代码：

library(ggplot2)
library(ggtext)
library(glue)

ggplot(mpg, aes(displ, hwy, color = class)) +
  geom_point() +
  scale_color_discrete(
    labels = ~ glue("<span style='color:{.color}'>{.x}</span>")
  ) +
  theme(
    legend.text = element_markdown(),
    legend.key = element_rect(fill = NA)
  )

内容的提问来源于stack exchange，提问作者Friedrich -- Слава Україні