Last active
February 27, 2017 17:02
-
-
Save phipsgabler/91a81883a82a54bb6a92 to your computer and use it in GitHub Desktop.
A new stat for ggplot2 creating the comparison line in a qq-plot.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
library(ggplot2) | |
qq.line <- function(data, qf, na.rm) { | |
# from stackoverflow.com/a/4357932/1346276 | |
q.sample <- quantile(data, c(0.25, 0.75), na.rm = na.rm) | |
q.theory <- qf(c(0.25, 0.75)) | |
slope <- diff(q.sample) / diff(q.theory) | |
intercept <- q.sample[1] - slope * q.theory[1] | |
list(slope = slope, intercept = intercept) | |
} | |
StatQQLine <- ggproto("StatQQLine", Stat, | |
# http://docs.ggplot2.org/current/vignettes/extending-ggplot2.html | |
# https://github.com/hadley/ggplot2/blob/master/R/stat-qq.r | |
required_aes = c('sample'), | |
compute_group = function(data, scales, | |
distribution = stats::qnorm, | |
dparams = list(), | |
na.rm = FALSE) { | |
qf <- function(p) do.call(distribution, c(list(p = p), dparams)) | |
n <- length(data$sample) | |
theoretical <- qf(stats::ppoints(n)) | |
qq <- qq.line(data$sample, qf = qf, na.rm = na.rm) | |
line <- qq$intercept + theoretical * qq$slope | |
data.frame(x = theoretical, y = line) | |
} | |
) | |
stat_qqline <- function(mapping = NULL, data = NULL, geom = "line", | |
position = "identity", ..., | |
distribution = stats::qnorm, | |
dparams = list(), | |
na.rm = FALSE, | |
show.legend = NA, | |
inherit.aes = TRUE) { | |
layer(stat = StatQQLine, data = data, mapping = mapping, geom = geom, | |
position = position, show.legend = show.legend, inherit.aes = inherit.aes, | |
params = list(distribution = distribution, | |
dparams = dparams, | |
na.rm = na.rm, ...)) | |
} | |
test.data <- data.frame(sample=rnorm(100, 10, 2)) | |
test.data.2 <- data.frame(sample=rt(100, df=2)) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
@UlvHare Hi, I'm sorry to respond so late, but apparently one doesn't get notified on gist comments...
Anyway, maybe I can find time to work on this next month. Probably one would have to clone some stuff from
geom_ribbon
into the functions, sincegeom_line
, which I used, by default doesn't allow to specify an additional ribbon. If you want to try it out yourself, this is actually the only ressource I've used.