geom_grob.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/geom-grob.R
\name{geom_grob}
\alias{geom_grob}
\alias{geom_grob_npc}
\title{Inset graphical objects}
\usage{
geom_grob(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  nudge_x = 0,
  nudge_y = 0,
  default.colour = "black",
  default.color = default.colour,
  colour.target = "segment",
  color.target = colour.target,
  default.alpha = 1,
  alpha.target = "segment",
  add.segments = TRUE,
  box.padding = 0.25,
  point.padding = 1e-06,
  segment.linewidth = 0.5,
  min.segment.length = 0,
  arrow = NULL,
  na.rm = FALSE,
  show.legend = FALSE,
  inherit.aes = FALSE
)

geom_grob_npc(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  na.rm = FALSE,
  show.legend = FALSE,
  inherit.aes = FALSE
)
}
\arguments{
\item{mapping}{The aesthetic mapping, usually constructed with
\code{\link[ggplot2]{aes}}. 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,
as a string.}

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

\item{...}{other arguments passed on to \code{\link[ggplot2]{layer}}. This
can include aesthetics whose values you want to set, not map. See
\code{\link[ggplot2]{layer}} for more details.}

\item{nudge_x, nudge_y}{Horizontal and vertical adjustments to nudge the
starting position of each text label. The units for \code{nudge_x} and
\code{nudge_y} are the same as for the data units on the x-axis and y-axis.}

\item{default.colour, default.color}{A colour definition to use for elements not targeted by
the colour aesthetic.}

\item{colour.target, color.target}{A vector of character strings; \code{"all"},
\code{"text"}, \code{"box"} and \code{"segment"} or \code{"none"}.}

\item{default.alpha}{numeric in [0..1] A transparency value to use for
elements not targeted by the alpha aesthetic.}

\item{alpha.target}{A vector of character strings; \code{"all"},
\code{"text"}, \code{"segment"}, \code{"box"}, \code{"box.line"}, and
\code{"box.fill"} or \code{"none"}.}

\item{add.segments}{logical Display connecting segments or arrows between
original positions and displaced ones if both are available.}

\item{box.padding, point.padding}{numeric By how much each end of the segments
should shortened in mm.}

\item{segment.linewidth}{numeric Width of the segments or arrows in mm.}

\item{min.segment.length}{numeric Segments shorter that the minimum length
are not rendered, in mm.}

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

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

\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[ggplot2]{borders}}.}
}
\value{
A plot layer instance.
}
\description{
\code{geom_grob} and \code{geom_grob_npc} add Grobs as insets to the ggplot
using syntax similar to that of \code{\link[ggplot2]{geom_text}},
\code{\link{geom_text_s}} and \code{\link{geom_text_npc}}.
In most respects they behave as any other ggplot geometry: they add a layer
containing one or more grobs and grouping and faceting works as usual. The
most common use of \code{geom_grob} is to add data labels that are graphical
objects rather than text. \code{\link{geom_grob_npc}} is used to add grobs
as annotations to plots, but contrary to layer function \code{annotate()},
\code{\link{geom_grob_npc}} is data driven and respects grouping and facets,
thus plot insets can differ among panels. Of these two geoms only
\code{\link{geom_grob}} supports the plotting of segments, as
\code{\link{geom_grob_npc}} uses a coordinate system that is unrelated
to data units and data.
}
\details{
You can modify the size of insets with the \code{vp.width} and
  \code{vp.height} aesthetics. These can take a number between 0 (smallest
  possible inset) and 1 (whole plotting area width or height). The default
  value for for both of these aesthetics is 1/5. Thus, in contrast to
  \code{\link[ggplot2]{geom_text}}, \code{\link[ggplot2]{geom_label}},
  \code{\link{geom_text_s}} and \code{\link{geom_label_s}} the size of the
  insets remains the same relative to the size of the plotting area
  irrespective of the size the plot is rendered at. The aspect ratio of
  insets is preserved and size is adjusted until the whole inset fits within
  the viewport.

  By default \code{geom_grob} uses \code{\link{position_nudge_center}} and
  justification \code{"position"}, while \code{geom_grob_npc} uses
  \code{\link[ggplot2]{position_nudge}} and justification \code{"inward"}. In
  contrast to \code{\link[ggplot2]{position_nudge}},
  \code{\link{position_nudge_center}} and all other position functions
  defined in packages 'ggpp' keep the original coordinates thus allowing the
  plotting of connecting segments and arrows.

  This \code{geom_grob} and \code{geom_grob_npc} require the use tibbles as
  argument for \code{data}, as the grobs should be stored as a list of
  graphics objects ("grob") to be mapped to the \code{label} aesthetic.

  The \code{x} and \code{y} aesthetics determine the position of the whole
  inset grob, similarly to that of a text label, justification is interpreted
  as indicating the position of the grob with respect to its \emph{x} and
  \emph{y} coordinates in the data, and \code{angle} is used to rotate the
  grob as a whole.
}
\note{
The insets are stored nested within the main ggplot object and
  contain their own copy of the data, and are rendered as grid grobs as normal
  ggplots at the time the main ggplot is rendered. They can have different
  themes.

  Use \code{\link{annotate}} as redefined in 'ggpp' when adding insets
  as annotations (automatically available unless 'ggpp' is not attached).
  \code{\link[ggplot2]{annotate}} cannot be used with the \code{npcx} and
  \code{npcy} pseudo-aesthetics.
}
\section{Plot boundaries and clipping}{
 The "width" and "height" of an inset
  as for a text element are 0, so stacking and dodging inset plots will not
  work by default, and axis limits are not automatically expanded to include
  all inset plots. Obviously, insets do have height and width, but they are
  physical units, not data units. The amount of space they occupy on the main
  plot is not constant in data units of the base plot: when you modify scale
  limits, inset plots stay the same size relative to the physical size of the
  base plot.
}

\section{Alignment}{
 You can modify text alignment with the \code{vjust} and
  \code{hjust} aesthetics. These can either be a number between 0
  (right/bottom) and 1 (top/left) or a character (\code{"left"},
  \code{"middle"}, \code{"right"}, \code{"bottom"}, \code{"center"},
  \code{"top"}). In addition, you can use special alignments for
  justification including \code{"position"}, \code{"inward"} and
  \code{"outward"}. Inward always aligns text towards the center of the
  plotting area, and outward aligns it away from the center of the plotting
  area. If tagged with \code{_mean} or \code{_median} (e.g.,
  \code{"outward_mean"}) the mean or median of the data in the panel along
  the corresponding axis is used as center. If the characters following the
  underscore represent a number (e.g., \code{"outward_10.5"}) the reference
  point will be this value in data units. Position justification is computed
  based on the direction of the displacement of the position of the label so
  that each individual text or label is justified outwards from its original
  position. The default justification is \code{"position"}.

  If no position displacement is applied, or a position function defined in
  'ggplot2' is used, these geometries behave similarly to the corresponding
  ones from package 'ggplot2' with a default justification of \code{0.5} and
  no segment drawn.
}

\section{Position functions}{
 Many layer functions from package 'ggpp' are
  designed to work seamlessly with position functions that keep, rather than
  discard, the original \code{x} and \code{y} positions in \code{data} when
  computing a new displaced position. See \code{\link{position_nudge_keep}},
  \code{\link{position_dodge_keep}}, \code{\link{position_jitter_keep}},
  \code{\link{position_nudge_center}}, \code{\link{position_nudge_line}},
  \code{\link{position_nudge_to}}, \code{\link{position_dodgenudge}},
  \code{\link{position_jitternudge}}, and \code{\link{position_stacknudge}}
  for examples and details of their use.
}

\examples{
library(tibble)
df <- tibble(x = 2, y = 15, grob = list(grid::circleGrob(r = 0.2)))

# without nudging no segments are drawn
ggplot(data = mtcars,
       aes(wt, mpg)) +
  geom_point(aes(colour = factor(cyl))) +
  geom_grob(data = df,
            aes(x, y, label = grob))

# with nudging segments are drawn
ggplot(data = mtcars,
       aes(wt, mpg)) +
  geom_point(aes(colour = factor(cyl))) +
  geom_grob(data = df,
            aes(x, y, label = grob),
            nudge_x = 0.5,
            colour = "red",
            hjust = 0.5,
            vjust = 0.5)

ggplot(data = mtcars,
       aes(wt, mpg)) +
  geom_point(aes(colour = factor(cyl))) +
  geom_grob(data = df,
            aes(x, y, label = grob),
            nudge_x = 0.5,
            colour = "red",
            colour.target = "none",
            hjust = 0.5,
            vjust = 0.5)

# with nudging plotting of segments can be disabled
ggplot(data = mtcars,
       aes(wt, mpg)) +
  geom_point(aes(colour = factor(cyl))) +
  geom_grob(data = df,
            aes(x, y, label = grob),
            add.segments = FALSE,
            nudge_x = 0.5,
            hjust = 0.5,
            vjust = 0.5)

}
\references{
The idea of implementing a \code{geom_custom()} for grobs has
  been discussed as an issue at
  \url{https://github.com/tidyverse/ggplot2/issues/1399}.
}
\seealso{
\code{\link[grid]{grid-package}}, \code{\link[ggplot2]{geom_text}},
  and other documentation of package 'ggplot2'.
}
\concept{geometries adding layers with insets.}