Connecting points to regression line in plot

ggplot2, lattice, plot, r

Solution

Prelim code

require("ggplot2")

mod <- loess(Income ~ Education, data = Income)
Income <- transform(Income, Fitted = fitted(mod))

ggplot version

ggplot(Income, aes(Education, Income)) + 
  geom_point(color="red") + 
  geom_smooth(se=FALSE, method = "loess") +
  geom_segment(aes(x = Education, y = Income,
                   xend = Education, yend = Fitted))

base graphics version

plot(Income ~ Education, data = Income, type = "p", col = "red",
     cex = 1.25)
points(Fitted ~ Education, data = Income)
lines(Fitted ~ Education, data = Income, col = "blue")
with(Income, segments(Education, Income, Education, Fitted))

Adjust accordingly to suit your aesthetic needs.

Problem

Consider the following data from the ISLR book: ``` Income <- structure(list(X = 1:30, Education = c(10, 10.4013377926421, 10.8428093645485, 11.2441471571906, 11.6454849498328, 12.0869565217391, 12.4882943143813, 12.8896321070234, 13.2909698996656, 13.7324414715719, 14.133779264214, 14.5351170568562, 14.9765886287625, 15.3779264214047, 15.7792642140468, 16.2207357859532, 16.6220735785953, 17.0234113712375, 17.4648829431438, 17.866220735786, 18.2675585284281, 18.7090301003344, 19.1103678929766, 19.5117056856187, 19.9130434782609, 20.3545150501672, 20.7558528428094, 21.1571906354515, 21.5986622073579, 22), Income = c(26.6588387834389, 27.3064353457772, 22.1324101716143, 21.1698405046065, 15.1926335164307, 26.3989510407284, 17.435306578572, 25.5078852305278, 36.884594694235, 39.666108747637, 34.3962805641312, 41.4979935356871, 44.9815748660704, 47.039595257834, 48.2525782901863, 57.0342513373801, 51.4909192102538, 61.3366205527288, 57.581988179306, 68.5537140185881, 64.310925303692, 68.9590086393083, 74.6146392793647, 71.8671953042483, 76.098135379724, 75.77521802986, 72.4860553152424, 77.3550205741877, 72.1187904524136, 80.2605705009016)), .Names = c("X", "Education", "Income"), class = "data.frame", row.names = c(NA, -30L)) ``` I want to reproduce their plot, which connects the points to the regression line to represent the error term, that is: It is easy to plot the points and the regression line with `ggplot2`: ``` ggplot(Income, aes(Education, Income)) + geom_point(color="red")+geom_smooth(se=FALSE) ``` But I could not think of an easy way to connect the points to the regression line like they did. Is there an easy way do it (with either `base`, `ggplot2` or `lattice`)?

Original source