Aggiungere linee tra certi livelli di leggenda nel ggplot2

Question

Ho un qualcosa di terreno come questo:

Si tratta di un grafico a mosaico dove c'è una linea nera sopra alcuni dei gruppi. Vorrei che anche quella linea nera fosse sulla leggenda. In questo esempio, la legenda ha 6 livelli e sopra i quadrati per i livelli 2 e 4 vorrei una linea nera.

Ho provato qualcosa del tipo: How to draw lines outside of plot area in ggplot2 ma sfortunatamente, poi quando ridimensiono la trama, le linee si muovono con la trama e non con la legenda e finiscono nel posto sbagliato.

Ecco il codice di esempio che ha reso la trama sopra.

exampledata<-data.frame(var1Center=c(rep(.2, 6) ,rep(.5,6) ,rep(.8,6)), 
         var2Height=c(.2,.2,.2,.1,.1,.2, .1,.1,.05,.45,.1,.2, .4,.07,.03,.1,.35,.05), 
         var1=c(rep("Thing 1", 6), rep("Thing 2", 6), rep("Thing 3", 6)), 
         var2=c(rep(c("A", "B", "C","D", "E", "F"), 3)), 
         marginVar1=c(rep(.4,6) ,rep(.2,6), rep(.4,6))) 

plotlines<-data.frame(xstart=c(0, 0,.4, .4, .6,.6), xstop=c(.4,.4, .6,.6, 1,1), value=c(.4, .7, .2,.7, .47, .6)) 

ggplot(exampledata, aes(var1Center, var2Height)) + 
    geom_bar(stat = "identity", aes(width = marginVar1, fill = var2)) + 
    scale_x_continuous(breaks=exampledata$var1Center, labels=exampledata$var1, expand=c(0,0))+ 
    theme_bw()+scale_y_continuous(name="Proportion",expand=c(0,0))+ 
    guides(fill = guide_legend(reverse=TRUE))+ 
    theme(panel.border=element_blank(), panel.grid=element_blank())+ 
    theme(axis.text.x=element_text(angle=90, hjust=1, vjust=.3))+ 
    geom_segment(data=plotlines, aes(x=xstart, xend=xstop, y=value, yend=value)) 

Answer 1

Ecco una soluzione che modifica il Grob leggenda. * Ho aggiunto una risposta più al di sotto che mostra come per esaminare la struttura Grob per aiutare a trovare proprietà che è possibile modificare.

* Sto solo imparando i grobs, quindi se qualcuno ha una soluzione su come aggiungere linesGrob() alla legenda, mi piacerebbe vederlo.

Risposta breve

p1 <- ggplot()... #Your original plot 

gt <- ggplotGrob(pl) #Convert plot to grob 
library(gtable); library(gridExtra) 
leg <- gtable_filter(gt, "guide-box") #Extract the legend 

#Modify the legend by adding a black line that is horizontal y = c(1,1) 
#sub-grob 8 is the teal box D 
    leg$grobs[[1]]$grobs[[1]]$grobs[[8]]$children[[2]]$gp$col <- "black" 
    leg$grobs[[1]]$grobs[[1]]$grobs[[8]]$children[[2]]$y <- unit(c(1,1), "npc") 
#sub-grob 12 is the brown box B 
    leg$grobs[[1]]$grobs[[1]]$grobs[[12]]$children[[2]]$gp$col <- "black" 
    leg$grobs[[1]]$grobs[[1]]$grobs[[12]]$children[[2]]$y <- unit(c(1,1), "npc") 

#Plot first plot with no legend, then add modified legend. 
p2 <- grid.arrange(p1 +theme(legend.position = "none"), leg, 
        ncol = 2, 
        widths = unit.c(unit(1, "npc") - sum(leg$width), sum(leg$width))) 

più lunga spiegazione Grobs sono strutturati come liste, in modo da utilizzare $ e [[]] per esplorare gli elementi della lista e senza nome, rispettivamente. Il comando str mostra l'oggetto str ucture.

str(leg) 
#List of 1 
#$ grobs :List of 1 
#..$ :List of 1 
#.. ..$ grobs :List of 1 
#.. .. ..$ 99_df28f764d4b38c6ac4aec87e00315c90:List of 20 
#.. .. .. ..$ grobs :List of 20 #<--Here is where we can find the legend boxes 
#.. .. .. .. ..$ :List of 10 
#.. .. .. .. .. ..$ x  :Class 'unit' atomic [1:1] 0.5 
#.. .. .. .. .. .. .. ..- attr(*, "unit")= chr "npc" 
#.. (snip) 

#'leg' has a named element 'grobs' with an unnamed list (' :List of 1'). 
#The first element of this unnamed list has a named sub-element 'grobs'. 
# which itself contains an unnamed list. 
#The next command goes down these branches of 'leg' to the sub-elements. 

leg$grobs[[1]]$grobs[[1]] #Elements of the legend are shown here 
#TableGrob (10 x 6) "layout": 20 grobs 
#z   cells  name        grob 
#1 1 (1-10, 1- 6) background rect[legend.background.rect.171] 
#2 2 (2- 2, 2- 5)  title  text[guide.title.text.127] 
#3 3 (4- 4, 2- 2) key-3-1-bg  rect[legend.key.rect.141] 
#4 4 (4- 4, 2- 2) key-3-1-1   gTree[GRID.gTree.142] 
#5 5 (5- 5, 2- 2) key-4-1-bg  rect[legend.key.rect.146] 
#6 6 (5- 5, 2- 2) key-4-1-1   gTree[GRID.gTree.147] 
#7 7 (6- 6, 2- 2) key-5-1-bg  rect[legend.key.rect.151] 
#8 8 (6- 6, 2- 2) key-5-1-1   gTree[GRID.gTree.152] 
#9 9 (7- 7, 2- 2) key-6-1-bg  rect[legend.key.rect.156] 
#10 10 (7- 7, 2- 2) key-6-1-1   gTree[GRID.gTree.157] 
#11 11 (8- 8, 2- 2) key-7-1-bg  rect[legend.key.rect.161] 
#12 12 (8- 8, 2- 2) key-7-1-1   gTree[GRID.gTree.162] 
#13 13 (9- 9, 2- 2) key-8-1-bg  rect[legend.key.rect.166] 
#14 14 (9- 9, 2- 2) key-8-1-1   gTree[GRID.gTree.167] 
#15 15 (4- 4, 4- 4) label-3-3  text[guide.label.text.129] 
#16 16 (5- 5, 4- 4) label-4-3  text[guide.label.text.131] 
#17 17 (6- 6, 4- 4) label-5-3  text[guide.label.text.133] 
#18 18 (7- 7, 4- 4) label-6-3  text[guide.label.text.135] 
#19 19 (8- 8, 4- 4) label-7-3  text[guide.label.text.137] 
#20 20 (9- 9, 4- 4) label-8-3  text[guide.label.text.139] 

#This table shows the structure of the legened, 
# where cells indicate (min.X-max.X, min.Y-max.Y). 
#The 8th element is one of the color keys as a gTree grob. 

#Examining this legend key box in more detail: 
leg$grobs[[1]]$grobs[[1]]$grobs[[8]]$children 
#(rect[GRID.rect.153], lines[GRID.lines.154]) 

#'children' is composed 2 sub-elements (in an unnamed list): rectangle and lines. 
#Exploring second sub-element (lines): 

#Line properties 
str(leg$grobs[[1]]$grobs[[1]]$grobs[[8]]$children[[2]]) 
#List of 6 
#$ x :Class 'unit' atomic [1:2] 0 1 
#.. ..- attr(*, "unit")= chr "npc" 
#.. ..- attr(*, "valid.unit")= int 0 
#$ y :Class 'unit' atomic [1:2] 0 1 
#.. ..- attr(*, "unit")= chr "npc" 
#.. ..- attr(*, "valid.unit")= int 0 
#$ arrow: NULL 
#$ name : chr "GRID.lines.154" 
#$ gp :List of 4 
#..$ col : logi NA 
#..$ lwd : num 1.42 
#..$ lineend: chr "butt" 
#..$ lty : num 1 
#..- attr(*, "class")= chr "gpar" 
#$ vp : NULL 
#- attr(*, "class")= chr [1:3] "lines" "grob" "gDesc" 

#Here we see the line goes left-right with $x = c(0,1) and top bottom with $y = c(0,1). 
# i.e. a bottom-left to top-right diagonal line. 
#This line is not actually plotted because it has no color: $gp$col = NA 

grid.draw(leg) #Show the legend 

#y and gp$col are changed as noted above.