r - 着色一点并在ggplot2中添加注释？

Question

我有一个a包含三列的数据框：

GeneName, Index1,Index2

我画了一个这样的散点图

ggplot(a, aes(log10(Index1+1), Index2)) +geom_point(alpha=1/5)

然后我想为一个点着色，并在该GeneName点"G1"附近添加一个文本框，最简单的方法是什么？

Answer 1

您可以创建一个仅包含该点的子集，然后将其添加到图中：

# create the subset
g1 <- subset(a, GeneName == "G1")

# plot the data
ggplot(a, aes(log10(Index1+1), Index2)) + geom_point(alpha=1/5) +  # this is the base plot
  geom_point(data=g1, colour="red") +  # this adds a red point
  geom_text(data=g1, label="G1", vjust=1) # this adds a label for the red point

注意：由于每个人都在对这个问题进行投票，我想我会让它更容易阅读。

Answer 2

像这样的东西应该工作。您可能需要弄乱x和的y参数geom_text()。

library(ggplot2)

highlight.gene <- "G1"

set.seed(23456)
a <- data.frame(GeneName = paste("G", 1:10, sep = ""),
                   Index1 = runif(10, 100, 200),
                   Index2 = runif(10, 100, 150))

a$highlight <- ifelse(a$GeneName == highlight.gene, "highlight", "normal")
textdf <- a[a$GeneName == highlight.gene, ]
mycolours <- c("highlight" = "red", "normal" = "grey50")

a
textdf

ggplot(data = a, aes(x = Index1, y = Index2)) +
    geom_point(size = 3, aes(colour = highlight)) +
    scale_color_manual("Status", values = mycolours) +
    geom_text(data = textdf, aes(x = Index1 * 1.05, y = Index2, label = "my label")) +
    theme(legend.position = "none") +
    theme()