r - 向 ggplot2 中的 x 轴添加小刻度线(无标签)

Question

下面是一个情节的示例代码，它几乎完全符合我的要求。我唯一想添加的是根据下面定义的 minor_breaks 在 x 轴上的刻度线(与主要刻度相同的大小)。

df <- data.frame(x = c(1900,1950,2000), y = c(50,75,60))

p <- ggplot(df, aes(x=x, y=y))
  p + geom_line() + 
  scale_x_continuous(minor_breaks = seq(1900,2000,by=10), breaks = seq(1900,2000,by=50), limits = c(1900,2000), expand = c(0,0)) +
  scale_y_continuous(breaks = c(20,40,60,80), limits = c(0,100)) +
  theme(legend.position="none", panel.background = element_blank(), 
  axis.line = element_line(color='black'), panel.grid.minor = element_blank())

提前致谢，
--JT

Answer 1

这将在精确的情况下做到这一点:

scale_x_continuous(breaks= seq(1900,2000,by=10), 
                  labels = c(1900, rep("",4), 1950, rep("",4), 2000), 
                  limits = c(1900,2000), expand = c(0,0)) +

这是一个不是防弹的函数，但可以在开始和结束主要标签与 at 的开始和停止值对齐时插入空白标签。争论:

insert_minor <- function(major_labs, n_minor) {labs <- 
                              c( sapply( major_labs, function(x) c(x, rep("", 4) ) ) )
                              labs[1:(length(labs)-n_minor)]}

测试:

p <- ggplot(df, aes(x=x, y=y))
  p + geom_line() + 
  scale_x_continuous(breaks= seq(1900,2000,by=10), 
                     labels = insert_minor( seq(1900, 2000, by=50), 4 ), 
                     limits = c(1900,2000), expand = c(0,0)) +
  scale_y_continuous(breaks = c(20,40,60,80), limits = c(0,100)) +
  theme(legend.position="none", panel.background = element_blank(), 
        axis.line = element_line(color='black'), panel.grid.minor = element_blank())