看看ggplot2中的箭头geom_segment()

Question

我正在尝试用ggplot2中的箭头绘制一个类似于此的图,这是使用基础R图形制作的.(颜色不重要)

使用ggplot2:

library(ggplot2)
library(scales)
library(grid)


df3 <- structure(list(value1 = c(51L, 57L, 59L, 57L, 56L, 56L, 60L, 
66L, 61L, 61L), value2 = c(56L, 60L, 66L, 61L, 61L, 59L, 61L, 
66L, 63L, 63L), group = c("A", "B", "C", "D", "E", "A", "B", 
"C", "D", "E"), time = c("1999", "1999", "1999", "1999", "1999", 
"2004", "2004", "2004", "2004", "2004"), y_position = c(1L, 2L, 
3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L)), .Names = c("value1", "value2", 
"group", "time", "y_position"), row.names = c(NA, -10L), class = "data.frame") 




ggplot( df3, aes( x = value1, y = y_position, group = time, color = time)) +

geom_segment( x = min(df3$value1, df3$value2),  xend = max( df3$value1, df3$value2 ),
              aes( yend = y_position), color = "lightgrey", size = 19)  +


scale_y_continuous(  labels = df3$group, breaks = df3$y_position) + 

theme_classic() + theme( axis.line = element_blank(), axis.title = element_blank()  ) + 

geom_segment( aes( yend = y_position, xend = value2, color = time, group = time), size = 19, alpha = 0.9,

              arrow = arrow(length = unit(40, "points"),type = "closed", angle = 40)  )

我明白了:

问题是箭头看起来不对(因为它们看起来不像第一个情节).使用geom_segment()并不重要.

这个问题可能会给出答案,但我希望不那么讨厌: 在R中为网格箭头指定gpar设置

Answer 1

更新:ggplot2 v2.1.0.9001

如果绘图位于当前窗口中,则可以直接使用编辑箭头的形状

grid.force()
# change shape of arrows
grid.gedit("segments", gp=gpar(linejoin ='mitre'))
# change the shape in legend also
grid.gedit("layout", gp=gpar(linejoin ='mitre'))

如果绘图位于当前窗口中,则可以直接使用编辑箭头的形状

grid.gedit("segments", gp=gpar(linejoin ='mitre'))

ggplot现在似乎已经将图例键更改为箭头形状,所以如果你想改变它们的形状,你可以在整个情节中做到这一点.

grid.gedit("gTableParent", gp=gpar(linejoin ='mitre'))

原始答案

不少hacky,但也许更容易？您可以编辑返回的grobs ggplotGrob.

如果p是你的情节:

g <-  ggplotGrob(p)

idx <- grep("panel", g$layout$name)

nms <- sapply(g$grobs[[idx]]$children[[3]]$children , '[[', "name")

for(i in nms) {
    g$grobs[[idx]]$children[[3]] <- 
              editGrob(g$grobs[[idx]]$children[[3]], nms[i], 
                        gp=gpar(linejoin ='mitre'), grep=TRUE)
}

grid.newpage()
grid.draw(g)

Answer 2

挑战似乎是,如果size在geom_segment块中调用,则网格包中的箭头构造函数会搞乱.

所以

p <- ggplot(df3) + coord_flip()

p1 <- p + geom_bar(aes(x=group,y=max(c(value1,value2))*1.1),width=0.2, stat="identity",position="identity",alpha=0.2)

df1<-filter(df3,time=="1999")

p1 + geom_segment(data=df1,aes(x=group,xend=group,y=value1,yend=value2),color="blue",size=8,arrow=arrow(angle=20,type="closed",ends="last",length=unit(1,"cm")))

你表现得看起来很荒谬.我尝试了将片段分成一个胖片段和一个瘦片段(两个层)上的箭头的解决方法,如下所示:

p2<-p1 + geom_segment(data=df1,aes(x=group,xend=group,y=value1,yend=value2), color="blue",arrow=arrow(angle=20,type="closed",ends="last",length=unit(1,"cm")))

p2 + geom_segment(data=df1,aes(x=group,xend=group,y=value1,yend=value2), color="blue",size=8)

但现在脂肪段末端没有减弱,因此遮挡了箭头.

arrow似乎需要修复参数.