R突出显示一条线上的一个点

Question

这是我生成情节的代码。你可以运行它：

library(ggplot2)
library(grid)
time <- c(87,87.5, 88,87,87.5,88)
value <- c(10.25,10.12,9.9,8,7,6)
variable <-c("a","a","a","b","b","b")
PointSize <-c(5,5,5,5,5,5)
ShapeType <-c(10,10,10,10,10,10)

stacked <- data.frame(time, value, variable, PointSize, ShapeType)

stacked$PointSize <- ifelse(stacked$time==88, 8, 5)
stacked$ShapeType <- ifelse(stacked$time==88, 16,10)

MyPlot <- ggplot(stacked, aes(x=time, y=value, colour=variable, group=variable)) + geom_line() + xlab("Strike") + geom_point(aes(shape = ShapeType, size = PointSize)) + theme(axis.text.x = element_text(angle = 90, hjust = 1), axis.text = element_text(size = 10),   axis.title=element_text(size=14),  plot.title = element_text(size = rel(2)) ,  legend.position = "bottom", legend.text = element_text(size = 10), legend.key.size = unit(1, "cm") ) + scale_shape_identity(guide="none")+scale_size_identity(guide="none")

MyPlot

生成的绘图突出显示时间= 88的行上的点。

我还要强调时间= 87.925

的行上的点

这可能吗？问题是我当时没有相应的价值。有没有办法找到时间= 87.925的线上的点或者是否需要进行一些插值，所以我可以得到一个该值的值？

谢谢！

Answer 1

您可以使用ggplot_build为每一行提取插值。 。 。

## create a fake ggplot to smooth your values using a linear fit ##
tmp.plot <- ggplot(stacked, aes(x = time, y = value, colour = variable)) + stat_smooth(method="lm")

## use ggplot_build to pull out the smoothing values ##
tmp.dat <- ggplot_build(tmp.plot)$data[[1]]

## find the x values closest to 87.925 for each variable ##
tmp.ids <- which(abs(tmp.dat$x - 87.925)<0.001)

## store the x and y values for each variable ##
new.points <- tmp.dat[tmp.ids,2:3]

## create a data frame with the new points ##
newpts <- data.frame(new.points,c("a","b"),c(8,8),c(16,16))

names(newpts) <- c("time","value","variable","PointSize","ShapeType")

## add the new points to your original data frame ##
stacked <- rbind(stacked,newpts)

## plot ##
MyPlot

Answer 2

您可以使用垂直线代替使用高亮显示87.925时间值的点：

ggplot(stacked, aes(x=time, y=value, colour=variable, group=variable)) +
  geom_line() +
  geom_point(aes(shape = ShapeType, size = PointSize)) +
  geom_vline(aes(xintercept=87.925)) +
  xlab("Strike") +
  theme(axis.text.x = element_text(angle = 90, hjust = 1), axis.text = element_text(size = 10),
        axis.title=element_text(size=14), plot.title = element_text(size = rel(2)), legend.position = "bottom",
        legend.text = element_text(size = 10), legend.key.size = unit(1, "cm")) +
  scale_shape_identity(guide="none") +
  scale_size_identity(guide="none")

结果：

---

更新：您可以使用geom_segment添加短行。将geom_vline替换为

geom_segment(aes(x = 87.925, y = 6, xend = 87.925, yend = 6.3), color="black") +
geom_segment(aes(x = 87.925, y = 9.8, xend = 87.925, yend = 10.05), color="black") +

导致：