R: Quantile regression

geom_quantile {ggplot2}

R Documentation

Quantile regression

Description

This fits a quantile regression to the data and draws the fitted quantiles with lines. This is as a continuous analogue to geom_boxplot().

Usage

geom_quantile(mapping = NULL, data = NULL, stat = "quantile",
  position = "identity", ..., lineend = "butt", linejoin = "round",
  linemitre = 10, na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)

stat_quantile(mapping = NULL, data = NULL, geom = "quantile",
  position = "identity", ..., quantiles = c(0.25, 0.5, 0.75),
  formula = NULL, method = "rq", method.args = list(), na.rm = FALSE,
  show.legend = NA, inherit.aes = TRUE)

Arguments

`mapping`	Set of aesthetic mappings created by `aes()` or `aes_()`. If specified and `inherit.aes = TRUE` (the default), it is combined with the default mapping at the top level of the plot. You must supply `mapping` if there is no plot mapping.
`data`	The data to be displayed in this layer. There are three options: If `NULL`, the default, the data is inherited from the plot data as specified in the call to `ggplot()`. A `data.frame`, or other object, will override the plot data. All objects will be fortified to produce a data frame. See `fortify()` for which variables will be created. A `function` will be called with a single argument, the plot data. The return value must be a `data.frame.`, and will be used as the layer data.
`position`	Position adjustment, either as a string, or the result of a call to a position adjustment function.
`...`	Other arguments passed on to `layer()`. These are often aesthetics, used to set an aesthetic to a fixed value, like `color = "red"` or `size = 3`. They may also be parameters to the paired geom/stat.
`lineend`	Line end style (round, butt, square).
`linejoin`	Line join style (round, mitre, bevel).
`linemitre`	Line mitre limit (number greater than 1).
`na.rm`	If `FALSE`, the default, missing values are removed with a warning. If `TRUE`, missing values are silently removed.
`show.legend`	logical. Should this layer be included in the legends? `NA`, the default, includes if any aesthetics are mapped. `FALSE` never includes, and `TRUE` always includes. It can also be a named logical vector to finely select the aesthetics to display.
`inherit.aes`	If `FALSE`, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g. `borders()`.
`geom, stat`	Use to override the default connection between `geom_quantile` and `stat_quantile`.
`quantiles`	conditional quantiles of y to calculate and display
`formula`	formula relating y variables to x variables
`method`	Quantile regression method to use. Currently only supports `quantreg::rq()`.
`method.args`	List of additional arguments passed on to the modelling function defined by `method`.

Aesthetics

geom_quantile understands the following aesthetics (required aesthetics are in bold):

x
y
alpha
colour
group
linetype
size
weight

Learn more about setting these aesthetics in vignette("ggplot2-specs")

Computed variables

quantile: quantile of distribution

Examples

m <- ggplot(mpg, aes(displ, 1 / hwy)) + geom_point()
m + geom_quantile()
m + geom_quantile(quantiles = 0.5)
q10 <- seq(0.05, 0.95, by = 0.05)
m + geom_quantile(quantiles = q10)

# You can also use rqss to fit smooth quantiles
m + geom_quantile(method = "rqss")
# Note that rqss doesn't pick a smoothing constant automatically, so
# you'll need to tweak lambda yourself
m + geom_quantile(method = "rqss", lambda = 0.1)

# Set aesthetics to fixed value
m + geom_quantile(colour = "red", size = 2, alpha = 0.5)

[Package ggplot2 version 3.0.0 Index]