r - Adding line of identity to correlation plots using pairs() command in R

Question

Similar to a prevous post, I'd like to modify the following code (from example in the R documentation for pairs() command):

## put (absolute) correlations on the upper panels,
## with size proportional to the correlations.
panel.cor <- function(x, y, digits = 2, prefix = "", cex.cor, ...)
{
    usr <- par("usr"); on.exit(par(usr))
    par(usr = c(0, 1, 0, 1))
    r <- abs(cor(x, y))
    txt <- format(c(r, 0.123456789), digits = digits)[1]
    txt <- paste0(prefix, txt)
    if(missing(cex.cor)) cex.cor <- 0.8/strwidth(txt)
    text(0.5, 0.5, txt, cex = cex.cor * r)
}
pairs(USJudgeRatings, lower.panel = panel.smooth, upper.panel = panel.cor)

Instead of a loess line, I want a line of identity for each plot. The secret lies in the $"panel.smooth" function, but I don't know how to modify it.

Answer 1

我想你的意思是这样的：

my_line <- function(x,y,...){
    points(x,y,...)
    abline(a = 0,b = 1,...)
}
pairs(USJudgeRatings, lower.panel = my_line, upper.panel = panel.cor)

Answer 2

或者，如果您想绘制一条拟合的线性线，那么您可以修改joran的答案：

my_line <- function(x,y,...){
    points(x,y,...)
    abline(a = lm(y ~ x)$coefficients[1] , b = lm(y ~ x)$coefficients[2] , ...)
}

但是，如果您确实使用了对，那么 loess 似乎更合适，因为您可能正在探索一个数据集，并且会保证此时线性线的拟合是无关的。