geom_line plot 与 colors

Question

我希望绘制计数与国家线 plot 并将颜色添加为 variant_type。 但是下面代码的 output 并不理想。

另外，我如何将我的 x-ticks 旋转 90 度？

谢谢

library(tidyverse)

countries <- c("America", "Brazil", "Canada", "America", "Brazil", "Canada")
count <- c(1, 2, 3, 2.5, 3, 4.5)
variant_type <- c("A", "A", "A", "B", "B", "B")

tbl <- tibble(countries, count, variant_type)

ggplot(data = tbl,
       aes(x = countries,
           y = count),
           color = variant_type) + 
  geom_line() + 
  theme_bw() + 
  theme(legend.position = "bottom",
        aspect.ratio = 3)