geom_path.Rd

% Generated by roxygen2 (4.1.1): do not edit by hand
% Please edit documentation in R/geom-line.r, R/geom-path.r, R/geom-step.r
\name{geom_line}
\alias{geom_line}
\alias{geom_path}
\alias{geom_step}
\title{Connect observations.}
\usage{
geom_line(mapping = NULL, data = NULL, stat = "identity",
  position = "identity", show.legend = NA, inherit.aes = TRUE,
  na.rm = TRUE, ...)

geom_path(mapping = NULL, data = NULL, stat = "identity",
  position = "identity", lineend = "butt", linejoin = "round",
  linemitre = 1, na.rm = FALSE, arrow = NULL, show.legend = NA,
  inherit.aes = TRUE, ...)

geom_step(mapping = NULL, data = NULL, stat = "identity",
  position = "identity", direction = "hv", show.legend = NA,
  inherit.aes = TRUE, ...)
}
\arguments{
\item{mapping}{Set of aesthetic mappings created by \code{\link{aes}} or
\code{\link{aes_}}. If specified and \code{inherit.aes = TRUE} (the
default), is combined with the default mapping at the top level of the
plot. You only need to supply \code{mapping} if there isn't a mapping
defined for the plot.}

\item{data}{A data frame. If specified, overrides the default data frame
defined at the top level of the plot.}

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

\item{position}{Position adjustment, either as a string, or the result of
a call to a position adjustment function.}

\item{show.legend}{logical. Should this layer be included in the legends?
\code{NA}, the default, includes if any aesthetics are mapped.
\code{FALSE} never includes, and \code{TRUE} always includes.}

\item{inherit.aes}{If \code{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. \code{\link{borders}}.}

\item{na.rm}{If \code{FALSE} (the default), removes missing values with
a warning.  If \code{TRUE} silently removes missing values.}

\item{...}{other arguments passed on to \code{\link{layer}}. There are
  three types of arguments you can use here:

  \itemize{
  \item Aesthetics: to set an aesthetic to a fixed value, like
     \code{color = "red"} or \code{size = 3}.
  \item Other arguments to the layer, for example you override the
    default \code{stat} associated with the layer.
  \item Other arguments passed on to the stat.
  }}

\item{lineend}{Line end style (round, butt, square)}

\item{linejoin}{Line join style (round, mitre, bevel)}

\item{linemitre}{Line mitre limit (number greater than 1)}

\item{arrow}{Arrow specification, as created by \code{\link[grid]{arrow}}}

\item{direction}{direction of stairs: 'vh' for vertical then horizontal, or
'hv' for horizontal then vertical}
}
\description{
\code{geom_path()} connects the observations in the order in which they appear
in the data. \code{geom_line()} connects them in order of the variable on the
x axis. \code{geom_step()} creates a stairstep plot, highlighting exactly
when changes occur.
}
\section{Aesthetics}{

\Sexpr[results=rd,stage=build]{ggplot2:::rd_aesthetics("geom", "path")}
}
\examples{
# geom_line() is suitable for time series
ggplot(economics, aes(date, unemploy)) + geom_line()
ggplot(economics_long, aes(date, value01, colour = variable)) +
  geom_line()

# geom_step() is useful when you want to highlight exactly when
# the y value chanes
recent <- economics[economics$date > as.Date("2013-01-01"), ]
ggplot(recent, aes(date, unemploy)) + geom_line()
ggplot(recent, aes(date, unemploy)) + geom_step()

# geom_path lets you explore how two variables are related over time,
# e.g. unemployment and personal savings rate
m <- ggplot(economics, aes(unemploy/pop, psavert))
m + geom_path()
m + geom_path(aes(colour = as.numeric(date)))

# Changing parameters ----------------------------------------------
ggplot(economics, aes(date, unemploy)) +
  geom_line(colour = "red")

# Use the arrow parameter to add an arrow to the line
# See ?arrow for more details
c <- ggplot(economics, aes(x = date, y = pop))
c + geom_line(arrow = arrow())
c + geom_line(
  arrow = arrow(angle = 15, ends = "both", type = "closed")
)

# Control line join parameters
df <- data.frame(x = 1:3, y = c(4, 1, 9))
base <- ggplot(df, aes(x, y))
base + geom_path(size = 10)
base + geom_path(size = 10, lineend = "round")
base + geom_path(size = 10, linejoin = "mitre", lineend = "butt")

# NAs break the line. Use na.rm = T to suppress the warning message
df <- data.frame(
  x = 1:5,
  y1 = c(1, 2, 3, 4, NA),
  y2 = c(NA, 2, 3, 4, 5),
  y3 = c(1, 2, NA, 4, 5)
)
ggplot(df, aes(x, y1)) + geom_point() + geom_line()
ggplot(df, aes(x, y2)) + geom_point() + geom_line()
ggplot(df, aes(x, y3)) + geom_point() + geom_line()

\donttest{
# Setting line type vs colour/size
# Line type needs to be applied to a line as a whole, so it can
# not be used with colour or size that vary across a line
x <- seq(0.01, .99, length.out = 100)
df <- data.frame(
  x = rep(x, 2),
  y = c(qlogis(x), 2 * qlogis(x)),
  group = rep(c("a","b"),
  each = 100)
)
p <- ggplot(df, aes(x=x, y=y, group=group))
# These work
p + geom_line(linetype = 2)
p + geom_line(aes(colour = group), linetype = 2)
p + geom_line(aes(colour = x))
# But this doesn't
should_stop(p + geom_line(aes(colour = x), linetype=2))
}
}
\seealso{
\code{\link{geom_polygon}}: Filled paths (polygons);
 \code{\link{geom_segment}}: Line segments
}