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ggplot2 (version 2.0.0)

geom_smooth: Add a smoothed conditional mean.

Description

Aids the eye in seeing patterns in the presence of overplotting. geom_smooth and stat_smooth are effectively aliases: they both use the same arguments. Use geom_smooth unless you want to display the results with a non-standard geom.

Usage

geom_smooth(mapping = NULL, data = NULL, stat = "smooth",
  method = "auto", formula = y ~ x, se = TRUE, position = "identity",
  na.rm = FALSE, show.legend = NA, inherit.aes = TRUE, ...)
stat_smooth(mapping = NULL, data = NULL, geom = "smooth",
  position = "identity", method = "auto", formula = y ~ x, se = TRUE,
  n = 80, span = 0.75, fullrange = FALSE, level = 0.95,
  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), is combined with the default mapping at the top le
data
A data frame. If specified, overrides the default data frame defined at the top level of the plot.
method
smoothing method (function) to use, eg. lm, glm, gam, loess, rlm. For datasets with n < 1000 default is loess. For datasets with 1000 or more observations defaults to gam, see
formula
formula to use in smoothing function, eg. y ~ x, y ~ poly(x, 2), y ~ log(x)
se
display confidence interval around smooth? (TRUE by default, see level to control
position
Position adjustment, either as a string, or the result of a call to a position adjustment function.
na.rm
If FALSE (the default), removes missing values with a warning. If TRUE silently removes missing values.
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.
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.
...
other arguments passed on to layer. There are three types of arguments you can use here:

  • Aesthetics: to set an aesthetic to a fixed value, likecolor = "red"orsize = 3.

geom, stat
Use to override the default connection between geom_smooth and stat_smooth.
n
number of points to evaluate smoother at
span
Controls the amount of smoothing for the default loess smoother. Smaller numbers produce wigglier lines, larger numbers produce smoother lines.
fullrange
should the fit span the full range of the plot, or just the data
level
level of confidence interval to use (0.95 by default)
method.args
List of additional arguments passed on to the modelling function defined by method.

Details

Calculation is performed by the (currently undocumented) predictdf generic and its methods. For most methods the standard error bounds are computed using the predict method - the exceptions are loess which uses a t-based approximation, and glm where the normal confidence interval is constructed on the link scale, and then back-transformed to the response scale.