r - geom_line : How to connect only a few points

Question

我有这个数据框和这个图:

df <- data.frame(Groupe = rep(c("A","B"),4),
                 Period = gl(4,2,8,c("t0","t1","t2","t3","t4")),
                 rate = c(0.83,0.96,0.75,0.93,0.67,0.82,0.65,0.73))

ggplot(data = df, mapping = aes(y = rate, x = Period ,group = Groupe, colour=Groupe, shape=Groupe)) +
   geom_line(size=1.2) +
   geom_point(size=5) 

我如何组织我的数据，以便 t1 之间的点和 t2不是用线连接的吗？我要 t0和 t1待连接(蓝色或红色根据组别)， t2和 t3以相同的方式连接，但 t1 之间没有线和 t2 .我通过查看类似的问题尝试了几件事，但它总是弄乱我的分组颜色:/

Answer 1

手动创建新的分组变量通常不是最好的方法。因此，一种稍微不同的方法需要较少的硬编码:

# create new grouping variable
df$grp <- c(1,2)[df$Period %in% c("t2","t3","t4") + 1L]

# create the plot and use the interaction between 'Group' and 'grp' as group
ggplot(df, aes(x = Period, y = rate,
               group = interaction(Groupe,grp),
               colour = Groupe,
               shape = Groupe)) +
  geom_line(size=1.2) +
  geom_point(size=5)

这给出了与另一个答案相同的情节: