r - ggplot2 - 如何并排绘制图表，只留下一个图例

Question

根据下面的示例数据集，我尝试制作 2 个图表并将它们并排放置。我尝试使用cowplot包来做到这一点。最终的输出真的很困惑。

有没有一种方法可以让我并排绘制它们，只显示 1 个图例，集中在底部(因为两个图都包含相同的元素)？

df <- data.frame(Year = c(rep(2012,5), rep(2016,5),
                          rep(2012,5), rep(2016,5),
                          rep(2012,5), rep(2016,5)),
                 Category = rep(c('A1','A2','A3','A4','A5'),6),
                 Group = rep(c('T1','T1','T1','T1','T1',
                           'T2','T2','T2','T2','T2',
                           'T3','T3','T3','T3','T3'),2),
                 Variable = runif(30,0,100))


plot2012 <- ggplot(df, aes(x = Group, y = Variable)) +
  geom_bar(aes(fill = Category), stat = 'identity') +
  ylim(0,500) +
  labs(y = 'Variable') +
  theme(legend.position = 'bottom',
        legend.title = element_blank(),
        axis.title = element_text(size = 10),
        legend.text = element_text(size = 10),
        axis.text = element_text(size = 10))

plot2016 <- ggplot(df, aes(x = Group, y = Variable)) +
  geom_bar(aes(fill = Category), stat = 'identity') +
  ylim(0,500) +
  labs(y = 'Variable') +
  theme(legend.position = 'bottom',
        legend.title = element_blank(),
        axis.title = element_text(size = 10),
        legend.text = element_text(size = 10),
        axis.text = element_text(size = 10))

欢迎对格式/代码提出任何其他一般性评论

Answer 1

您可以将 facet_grid 添加到您的 ggplot 调用中。

ggplot(df, aes(x = Group, y = Variable)) +
  geom_bar(aes(fill = Category), stat = 'identity') +
  ylim(0,500) +
  labs(y = 'Variable') +
  # Generate plots as panel based on Year
  facet_grid(. ~ Year) +
  theme(legend.position = 'bottom',
        legend.title = element_blank(),
        axis.title = element_text(size = 10),
        legend.text = element_text(size = 10),
        axis.text = element_text(size = 10))