ggplot，在各个面之间的点之间画线
使用ggplot2，我如何绘制在各个方面之间运行的趋势线。
library(ggplot2) df <- data.frame(y=c(1,2,3),x=1,Set=LETTERS[1:3]) ggplot(df,aes(x,y)) + theme_bw() + theme(legend.position=c(0,1),legend.justification=c(0,1)) + geom_point(aes(fill=Set),color="black",shape=21,size=3) + facet_grid(~Set) + xlim(1,5) 其中产生以下内容：
在上面，我想在三点之间划一条线，穿过各个方面。
你可以做到这一点，但closures剪辑可能会有不必要的后果，
library(ggplot2) df <- data.frame(y=c(1,2,3),x=1,Set=LETTERS[1:3]) p <- ggplot(df,aes(x,y)) + theme_bw() + theme(legend.position=c(0,1),legend.justification=c(0,1)) + geom_point(aes(fill=Set),color="black",shape=21,size=3) + facet_grid(~Set) + xlim(1,5) gb <- ggplot_build(p) g <- ggplot_gtable(gb) library(gtable) # ggplot2 doesn't use native units in data space # instead, the data is rescaled to npc, ie from 0 to 1 # so we need to use the build info to convert from data to [0,1] ranges <- gb$layout$panel_ranges data2npc <- function(x, range) scales::rescale(c(range, x), c(0,1))[-c(1,2)] start <- c(data2npc(1, ranges[[1]][["x.range"]]), data2npc(1, ranges[[1]][["y.range"]])) end <- c(data2npc(1, ranges[[3]][["x.range"]]), data2npc(3, ranges[[3]][["y.range"]])) # starting position in the first panel g <- gtable_add_grob(g, moveToGrob(start[1],start[2]), t = 7, l = 4) # draw line to end position in last panel g <- gtable_add_grob(g, lineToGrob(end[1],end[2]), t = 7, l = 8, r=8, z=Inf) # turn clip off to see the line across panels g$layout$clip <- "off" grid.newpage() grid.draw(g)
