在ggplot2生成的图表下方显示文本

Question

我试图在ggplot2中创建的图表下面显示一些有关数据的信息.我想使用图的X轴坐标绘制N变量,但Y坐标需要距离屏幕底部10%.实际上,期望的Y坐标已经作为y_pos变量存在于数据框中.

我可以想到使用ggplot2的3种方法:

1)在实际绘图下方创建一个空图,使用相同的比例,然后使用geom_text在空白图上绘制数据.这种方法有点有效,但非常复杂.

2)geom_text用于绘制数据,但以某种方式使用y坐标作为屏幕的百分比(10%).这将强制数字显示在图表下方.我无法弄清楚正确的语法.

3)使用grid.text显示文本.我可以轻松地将它设置在屏幕底部的10%,但我无法确定如何设置X coordindate以匹配绘图.我试图使用grconvert捕获最初的X位置但是也无法使其工作.

以下是虚拟数据的基本情节:

graphics.off()      # close graphics windows   

library(car)
library(ggplot2)  #load ggplot
library(gridExtra) #load Grid
library(RGraphics) # support of the "R graphics" book, on CRAN

#create dummy data
test= data.frame(
  Group = c("A", "B", "A","B", "A", "B"), 
  x = c(1 ,1,2,2,3,3 ),
  y = c(33,25,27,36,43,25),
  n=c(71,55,65,58,65,58),
  y_pos=c(9,6,9,6,9,6)
  )

#create ggplot
p1 <- qplot(x, y, data=test, colour=Group) +
  ylab("Mean change from baseline") + 
  geom_line()+
  scale_x_continuous("Weeks", breaks=seq(-1,3, by = 1) ) +
  opts( 
        legend.position=c(.1,0.9))

#display plot
p1

下面的修改后的gplot显示了主题数量,但它们显示在绘图中.它们迫使Y标度延长.我想在情节下面显示这些数字.

    p1 <- qplot(x, y, data=test, colour=Group) +
  ylab("Mean change from baseline") + 
  geom_line()+
  scale_x_continuous("Weeks", breaks=seq(-1,3, by = 1) ) +
  opts( plot.margin = unit(c(0,2,2,1), "lines"),
        legend.position=c(.1,0.9))+
  geom_text(data = test,aes(x=x,y=y_pos,label=n))

p1

显示数字的另一种方法是在实际绘图下方创建虚拟绘图.这是代码:

graphics.off()      # close graphics windows   

library(car)
library(ggplot2)  #load ggplot
library(gridExtra) #load Grid
library(RGraphics) # support of the "R graphics" book, on CRAN

#create dummy data
test= data.frame(
  group = c("A", "B", "A","B", "A", "B"), 
  x = c(1 ,1,2,2,3,3 ),
  y = c(33,25,27,36,43,25),
  n=c(71,55,65,58,65,58),
  y_pos=c(15,6,15,6,15,6)
  )


p1 <- qplot(x, y, data=test, colour=group) +
  ylab("Mean change from baseline") + 
  opts(plot.margin = unit(c(1,2,-1,1), "lines")) +
  geom_line()+
  scale_x_continuous("Weeks", breaks=seq(-1,3, by = 1) ) +
  opts(legend.position="bottom",
       legend.title=theme_blank(),
       title.text="Line plot using GGPLOT") 
p1

p2 <- qplot(x, y, data=test, geom="blank")+
  ylab(" ")+
  opts(     plot.margin = unit(c(0,2,-2,1), "lines"),
            axis.line = theme_blank(), 
            axis.ticks = theme_segment(colour = "white"),           
            axis.text.x=theme_text(angle=-90,colour="white"),
            axis.text.y=theme_text(angle=-90,colour="white"),
            panel.background = theme_rect(fill = "transparent",colour = NA), 
            panel.grid.minor = theme_blank(),      
            panel.grid.major = theme_blank()
            )+
  geom_text(data = test,aes(x=x,y=y_pos,label=n)) 
p2

grid.arrange(p1, p2, heights = c(8.5, 1.5),             nrow=2 )

然而,这非常复杂,并且难以针对不同数据进行修改.理想情况下,我希望能够将Y坐标作为屏幕的百分比传递.

Answer 1

opts已编辑已被弃用,取而代之theme; element_blank已经取代theme_blank; 而ggtitle()代替使用opts(title = ...

桑迪 - 非常感谢你!!!! 这正是我想要的.我希望我们可以控制geom.text或geom.annotate中的剪辑.

如果有其他人有兴趣,我会把以下程序放在一起.

 rm(list = ls())     # clear objects  
 graphics.off()      # close graphics windows   

library(ggplot2)
library(gridExtra)

#create dummy data
test= data.frame(
  group = c("Group 1", "Group 1", "Group 1","Group 2", "Group 2", "Group 2"), 
  x = c(1 ,2,3,1,2,3 ),
  y = c(33,25,27,36,23,25),
  n=c(71,55,65,58,65,58),
  ypos=c(18,18,18,17,17,17)

  )


p1 <- qplot(x=x, y=y, data=test, colour=group) +
  ylab("Mean change from baseline") + 
  theme(plot.margin = unit(c(1,3,8,1), "lines")) +
  geom_line()+
  scale_x_continuous("Visits", breaks=seq(-1,3) ) +
  theme(legend.position="bottom",
       legend.title=element_blank())+
   ggtitle("Line plot") 


# Create the textGrobs 
for (ii in 1:nrow(test))
{
  #display numbers at each visit
  p1=p1+ annotation_custom(grob = textGrob(test$n[ii]),  
                           xmin = test$x[ii], 
                           xmax = test$x[ii], 
                           ymin = test$ypos[ii], 
                           ymax = test$ypos[ii])

    #display group text
    if (ii %in% c(1,4)) #there is probably a better way 
      {
    p1=p1+ annotation_custom(grob = textGrob(test$group[ii]),  
                             xmin = 0.85, 
                             xmax = 0.85, 
                             ymin = test$ypos[ii], 
                             ymax = test$ypos[ii])
    }

  }




  # Code to override clipping
  gt <- ggplot_gtable(ggplot_build(p1))
  gt$layout$clip[gt$layout$name=="panel"] <- "off"
  grid.draw(gt)

Answer 2

当前版本(> 2.1)有一个+ labs(caption = "text"),在图表下方显示注释.这是可以设置的(字体属性,...左/右对齐).有关示例,请参阅https://github.com/hadley/ggplot2/pull/1582.

Answer 3

更新 opts()已被替换为theme()

在下面的代码中,绘制了一个基本图,在图的底部有一个更宽的边距.创建textGrob,然后使用annotation_custom()将其插入到绘图中.除了文本不可见,因为它在绘图面板之外 - 输出被剪切到面板.但是从这里使用baptiste的代码,剪辑可以被覆盖.位置以数据单位表示,两个文本标签都居中.

library(ggplot2)
library(grid)

# Base plot
df = data.frame(x=seq(1:10), y = seq(1:10))
p = ggplot(data = df, aes(x = x, y = y)) + geom_point() + ylim(0,10) +
    theme(plot.margin = unit(c(1,1,3,1), "cm"))
p

# Create the textGrobs
Text1 = textGrob(paste("Largest x-value is", round(max(df$x), 2), sep = " "))
Text2 = textGrob(paste("Mean = ", mean(df$x), sep = ""))

p1 = p + annotation_custom(grob = Text1,  xmin = 4, xmax = 4, ymin = -3, ymax = -3) +
        annotation_custom(grob = Text2,  xmin = 8, xmax = 8, ymin = -3, ymax = -3)
p1

# Code to override clipping
gt <- ggplotGrob(p1)
gt$layout$clip[gt$layout$name=="panel"] <- "off"
grid.draw(gt)

或者,使用grid函数来创建和定位标签.

p
grid.text((paste("Largest x-value is", max(df$x), sep = " ")),
   x = unit(.2, "npc"), y = unit(.1, "npc"), just = c("left", "bottom"), 
   gp = gpar(fontface = "bold", fontsize = 18, col = "blue"))

编辑 或,使用gtable函数添加文本grob.

library(ggplot2)
library(grid)
library(gtable)

# Base plot
df = data.frame(x=seq(1:10), y = seq(1:10))
p = ggplot(data = df, aes(x = x, y = y)) + geom_point() + ylim(0,10) 

# Construct the text grob
lab = textGrob((paste("Largest x-value is", max(df$x), sep = " ")),
   x = unit(.1, "npc"), just = c("left"), 
   gp = gpar(fontface = "bold", fontsize = 18, col = "blue"))


gp = ggplotGrob(p)

# Add a row below the 2nd from the bottom
gp = gtable_add_rows(gp, unit(2, "grobheight", lab), -2)

# Add 'lab' grob to that row, under the plot panel
gp = gtable_add_grob(gp, lab, t = -2, l = gp$layout[gp$layout$name == "panel",]$l)

grid.newpage()
grid.draw(gp)

Answer 4

实际上,最好的答案和最简单的解决方案是使用cowplot包.

牛皮图包的版本0.5.0(在CRAN上)使用add_sub函数处理ggplot2字幕.

像这样使用它:

  diamondsCubed <-ggplot(aes(carat, price), data = diamonds) + 
  geom_point() + 
  scale_x_continuous(trans = cuberoot_trans(), limits = c(0.2, 3),
                     breaks = c(0.2, 0.5, 1, 2, 3)) + 
  scale_y_continuous(trans = log10_trans(), limits = c(350, 15000),
                     breaks = c(350, 1000, 5000, 10000, 15000)) +
  ggtitle('Price log10 by Cube-Root of Carat') +
  theme_xkcd()


  ggdraw(add_sub(diamondsCubed, "This is an annotation.\nAnnotations can span multiple lines."))