geom_qq
and stat_qq
produce quantilequantile plots. geom_qq_line
and
stat_qq_line
compute the slope and intercept of the line connecting the
points at specified quartiles of the theoretical and sample distributions.
geom_qq_line(mapping = NULL, data = NULL, geom = "path", position = "identity", ..., distribution = stats::qnorm, dparams = list(), line.p = c(0.25, 0.75), fullrange = FALSE, na.rm = FALSE, show.legend = NA, inherit.aes = TRUE) stat_qq_line(mapping = NULL, data = NULL, geom = "path", position = "identity", ..., distribution = stats::qnorm, dparams = list(), line.p = c(0.25, 0.75), fullrange = FALSE, na.rm = FALSE, show.legend = NA, inherit.aes = TRUE) geom_qq(mapping = NULL, data = NULL, geom = "point", position = "identity", ..., distribution = stats::qnorm, dparams = list(), na.rm = FALSE, show.legend = NA, inherit.aes = TRUE) stat_qq(mapping = NULL, data = NULL, geom = "point", position = "identity", ..., distribution = stats::qnorm, dparams = list(), na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)
mapping  Set of aesthetic mappings created by 

data  The data to be displayed in this layer. There are three options: If A A 
geom  The geometric object to use display the data 
position  Position adjustment, either as a string, or the result of a call to a position adjustment function. 
...  Other arguments passed on to 
distribution  Distribution function to use, if x not specified 
dparams  Additional parameters passed on to 
line.p  Vector of quantiles to use when fitting the QQ line, defaults
defaults to 
fullrange  Should the qq line span the full range of the plot, or just the data 
na.rm  If 
show.legend  logical. Should this layer be included in the legends?

inherit.aes  If 
stat_qq()
understands the following aesthetics (required aesthetics are in bold):
sample
group
x
y
Learn more about setting these aesthetics in vignette("ggplot2specs")
.
stat_qq_line()
understands the following aesthetics (required aesthetics are in bold):
sample
group
x
y
Learn more about setting these aesthetics in vignette("ggplot2specs")
.
Variables computed by stat_qq
:
sample quantiles
theoretical quantiles
Variables computed by stat_qq_line
:
xcoordinates of the endpoints of the line segment connecting the points at the chosen quantiles of the theoretical and the sample distributions
ycoordinates of the endpoints
df < data.frame(y = rt(200, df = 5)) p < ggplot(df, aes(sample = y)) p + stat_qq() + stat_qq_line()# Use fitdistr from MASS to estimate distribution params params < as.list(MASS::fitdistr(df$y, "t")$estimate)#> Warning: NaNs producedggplot(df, aes(sample = y)) + stat_qq(distribution = qt, dparams = params["df"]) + stat_qq_line(distribution = qt, dparams = params["df"])