绘图中缺少图例

import matplotlib.pyplot as plt

# 示例数据
x = [1, 2, 3, 4]
y1 = [10, 15, 7, 10]
y2 = [16, 5, 11, 9]

# 绘图
plt.plot(x, y1, label='Series 1')
plt.plot(x, y2, label='Series 2')

# 添加图例
plt.legend(loc='upper right')

# 显示图表
plt.show()

import seaborn as sns
import matplotlib.pyplot as plt

# 示例数据
tips = sns.load_dataset('tips')

# 绘图
sns.scatterplot(x='total_bill', y='tip', hue='sex', data=tips)

# 添加图例
plt.legend(title='Sex')

# 显示图表
plt.show()

library(ggplot2)

# 示例数据
data <- data.frame(
  x = c(1, 2, 3, 4),
  y = c(10, 15, 7, 10),
  group = c('A', 'B', 'A', 'B')
)

# 绘图
ggplot(data, aes(x = x, y = y, color = group)) +
  geom_point() +
  theme_minimal() +
  labs(color = "Group")