geom_errorbar.Rd

% Generated by roxygen2 (4.0.0): do not edit by hand
\name{geom_errorbar}
\alias{geom_errorbar}
\title{Error bars.}
\usage{
geom_errorbar(mapping = NULL, data = NULL, stat = "identity",
  position = "identity", ...)
}
\arguments{
\item{mapping}{The aesthetic mapping, usually constructed with
\code{\link{aes}} or \code{\link{aes_string}}. Only needs to be set
at the layer level if you are overriding the plot defaults.}

\item{data}{A layer specific dataset - only needed if you want to override
the plot defaults.}

\item{stat}{The statistical transformation to use on the data for this
layer.}

\item{position}{The position adjustment to use for overlapping points
on this layer}

\item{...}{other arguments passed on to \code{\link{layer}}. This can
include aesthetics whose values you want to set, not map. See
\code{\link{layer}} for more details.}
}
\description{
Error bars.
}
\section{Aesthetics}{

\Sexpr[results=rd,stage=build]{ggplot2:::rd_aesthetics("geom", "errorbar")}
}
\examples{
# Create a simple example dataset
df <- data.frame(
  trt = factor(c(1, 1, 2, 2)),
  resp = c(1, 5, 3, 4),
  group = factor(c(1, 2, 1, 2)),
  se = c(0.1, 0.3, 0.3, 0.2)
)
df2 <- df[c(1,3),]

# Define the top and bottom of the errorbars
limits <- aes(ymax = resp + se, ymin=resp - se)

p <- ggplot(df, aes(fill=group, y=resp, x=trt))
p + geom_bar(position="dodge", stat="identity")

# Because the bars and errorbars have different widths
# we need to specify how wide the objects we are dodging are
dodge <- position_dodge(width=0.9)
p + geom_bar(position=dodge) + geom_errorbar(limits, position=dodge, width=0.25)

p <- ggplot(df2, aes(fill=group, y=resp, x=trt))
p + geom_bar(position=dodge)
p + geom_bar(position=dodge) + geom_errorbar(limits, position=dodge, width=0.25)

p <- ggplot(df, aes(colour=group, y=resp, x=trt))
p + geom_point() + geom_errorbar(limits, width=0.2)
p + geom_pointrange(limits)
p + geom_crossbar(limits, width=0.2)

# If we want to draw lines, we need to manually set the
# groups which define the lines - here the groups in the
# original dataframe
p + geom_line(aes(group=group)) + geom_errorbar(limits, width=0.2)
}
\seealso{
\code{\link{geom_pointrange}}: range indicated by straight line,
  with point in the middle; \code{\link{geom_linerange}}: range indicated
  by straight line; \code{\link{geom_crossbar}}: hollow bar with middle
  indicated by horizontal line; \code{\link{stat_summary}}: examples of
  these guys in use, \code{\link{geom_smooth}} for continuous analog
}