R语言 如何为图片添加文字说明（转载）

转载：(中文翻译者)[http://blog.csdn.net/chen790646223/article/details/49766659]
(原文链接)[http://datascienceplus.com/adding-text-to-r-plot/ ]

下面介绍了n中为图片添加文字的方法。

# 利用layout函数分割屏幕
layout(matrix(c(1,1,2,2), 2, 2, byrow = T), heights = c(4,1))

# 随意画一张图
plot(rnorm(10),ylab="", xlab="Use the xlab argument", main="Use the title", ty="o", pch=19)

# 添加文字说明
mtext("Use the mtext() function")
temp <- locator(1) # 在图表上，你喜欢的地方点击一下，文字就出来了
text(temp,"Use the text() with or without the locator() function")

# 用下面的Corner_text函数添加文字（自己编写的函数）:
Corner_text <- function(text, location="topright"){
legend(location,legend=text, bty ="n", pch=NA) 
}
Corner_text(text="Use Corner_text() function")
Corner_text(text="Use the Corner_text() function",location= "bottomright")

# 利用函数title 添加文字说明 
title(sub="Add subtitle using the title() function")

# 利用包gplots添加更多文字
library(gplots)

# ?textplot # 查询这个包的信息

# layout.show(2) # 在分割屏幕的中间显示内容（上面的屏幕和下面的屏幕之间）
temptext1 <- "Add here notes. The plot above represents 10 random points drawn from Normal distribution. The plot is generated in order 
to visualize all the different options one can use for adding text to a plot. 
You can control this text size using the usual \"cex\" argument.
\nYou can increase readability if you skip lines. 
\nUse this space when you have complicated charts that require some more details. Add explanations and preemt possible questions, by that 
saving readers' time (e.g. \"is it percentage or basis points?\" )."
temptext2 <-  "You can also add more text in the usual way by using again the locator(1)+text() functions" 
textplot(temptext1, valign="center", cex=0.8, halign= "left", mar=c(0,0,0,0), col=2) 

# mar=c(0,0,0,0) 除去页面空白
temp <- locator(1)
text(temp, temptext2,col=4)