Q-Q plot with ggplot2::stat_qq, colours, single group

Question

I\'m looking for a more convenient way to get a Q-Q plot in ggplot2 where the quantiles are computed for the data set as a whole. but I can use mappings (colour

Answer 1

You could calculate the quantiles yourself and then plot using geom_point:

dda = cbind(dda, setNames(qqnorm(dda$.resid, plot.it=FALSE), c("Theoretical", "Sample")))

ggplot(dda) + 
  geom_point(aes(x=Theoretical, y=Sample, colour=f))

Ah, I guess I should have read to the end of your question. This is the manual solution you were referring to, right? Although you could just package it as a function:

my_stat_qq = function(data, colour.var) {

  data=cbind(data, setNames(qqnorm(data$.resid, plot.it=FALSE), c("Theoretical", "Sample")))

  ggplot(data) + 
    geom_point(aes_string(x="Theoretical", y="Sample", colour=colour.var))

}

my_stat_qq(dda, "f")