Question

I would like to create multiple scatterplots with lines joining all the point in each hospital group.

> head(dt.gg)

        pred   base hospital
1 -1.4273910 -2.596        1
2 -0.7296839 -1.595        1
3 -0.6606799 -1.496        1
4 -0.5993430 -1.408        1
5 -0.5380061 -1.320        1
6 -0.4766692 -1.232        1

My attempt so far is :

require(ggplot2)
dt.gg <- read.csv("http://goo.gl/5yjEZ")
ggplot(dt.gg, aes(x=base, y=pred, color=hospital)) + geom_point(shape=1) +
    theme(legend.position="none") 

But I have been unable to join the dots in each group. geom_line() does not seem to work – it joins all the point, rather than joining the points in each hospital group seperately (and with the same colour as the point for each group)

Answer 1

You should add argument group=hospital to function ggplot() to join points.

ggplot(dt.gg, aes(x=base, y=pred, color=hospital,group=hospital)) + geom_point(shape=1) +
 geom_line()+ theme(legend.position="none")