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Textual annotations.

Source: R/geom-label.R, R/geom-text.r
geom_text.Rd

geom_text adds text directly to the plot. geom_label draws a rectangle underneath the text, making it easier to read.

Usage

geom_label(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  parse = FALSE,
  nudge_x = 0,
  nudge_y = 0,
  label.padding = unit(0.25, "lines"),
  label.r = unit(0.15, "lines"),
  label.size = 0.25,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

geom_text(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  parse = FALSE,
  nudge_x = 0,
  nudge_y = 0,
  check_overlap = FALSE,
  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.

stat

The statistical transformation to use on the data for this layer, as a string.

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.

parse

If TRUE, the labels will be parsed into expressions and displayed as described in ?plotmath

nudge_x, nudge_y

Horizontal and vertical adjustment to nudge labels by. Useful for offsetting text from points, particularly on discrete scales.

label.padding

Amount of padding around label. Defaults to 0.25 lines.

label.r

Radius of rounded corners. Defaults to 0.15 lines.

label.size

Size of label border, in mm.

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. borders.

check_overlap

If TRUE, text that overlaps previous text in the same layer will not be plotted. A quick and dirty way

Details

Note the the "width" and "height" of a text element are 0, so stacking and dodging text will not work by default, and axis limits are not automatically expanded to include all text. Obviously, labels do have height and width, but they are physical units, not data units. The amount of space they occupy on that plot is not constant in data units: when you resize a plot, labels stay the same size, but the size of the axes changes.

Aesthetics

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

  • label

  • x

  • y

  • alpha

  • angle

  • colour

  • family

  • fontface

  • hjust

  • lineheight

  • size

  • vjust

geom_label

Currently geom_label does not support the rot parameter and is considerably slower than geom_text. The fill aesthetic controls the background colour of the label.

Alignment

You can modify text alignment with the vjust and hjust aesthetics. These can either be a number between 0 (right/bottom) and 1 (top/left) or a character ("left", "middle", "right", "bottom", "center", "top"). There are two special alignments: "inward" and "outward". Inward always aligns text towards the center, and outward aligns it away from the center

Examples

p <- ggplot(mtcars, aes(wt, mpg, label = rownames(mtcars)))

p + geom_text()

# Avoid overlaps
p + geom_text(check_overlap = TRUE)

# Labels with background
p + geom_label()

# Change size of the label
p + geom_text(size = 10)


# Set aesthetics to fixed value
p + geom_point() + geom_text(hjust = 0, nudge_x = 0.05)

p + geom_point() + geom_text(vjust = 0, nudge_y = 0.5)

p + geom_point() + geom_text(angle = 45)

if (FALSE) { # \dontrun{
# Doesn't work on all systems
p + geom_text(family = "Times New Roman")
} # }

# Add aesthetic mappings
p + geom_text(aes(colour = factor(cyl)))

p + geom_text(aes(colour = factor(cyl))) +
  scale_colour_discrete(l = 40)

p + geom_label(aes(fill = factor(cyl)), colour = "white", fontface = "bold")


p + geom_text(aes(size = wt))

# Scale height of text, rather than sqrt(height)
p + geom_text(aes(size = wt)) + scale_radius(range = c(3,6))


# You can display expressions by setting parse = TRUE.  The
# details of the display are described in ?plotmath, but note that
# geom_text uses strings, not expressions.
p + geom_text(aes(label = paste(wt, "^(", cyl, ")", sep = "")),
  parse = TRUE)


# Add a text annotation
p +
  geom_text() +
  annotate("text", label = "plot mpg vs. wt", x = 2, y = 15, size = 8, colour = "red")


# \donttest{
# Aligning labels and bars --------------------------------------------------
df <- data.frame(
  x = factor(c(1, 1, 2, 2)),
  y = c(1, 3, 2, 1),
  grp = c("a", "b", "a", "b")
)

# ggplot2 doesn't know you want to give the labels the same virtual width
# as the bars:
ggplot(data = df, aes(x, y, fill = grp, label = y)) +
  geom_bar(stat = "identity", position = "dodge") +
  geom_text(position = "dodge")
#> Warning: Width not defined. Set with `position_dodge(width = ?)`

# So tell it:
ggplot(data = df, aes(x, y, fill = grp, label = y)) +
  geom_bar(stat = "identity", position = "dodge") +
  geom_text(position = position_dodge(0.9))

# Use you can't nudge and dodge text, so instead adjust the y postion
ggplot(data = df, aes(x, y, fill = grp, label = y)) +
  geom_bar(stat = "identity", position = "dodge") +
  geom_text(aes(y = y + 0.05), position = position_dodge(0.9), vjust = 0)


# To place text in the middle of each bar in a stacked barplot, you
# need to do the computation yourself
df <- transform(df, mid_y = ave(df$y, df$x, FUN = function(val) cumsum(val) - (0.5 * val)))

ggplot(data = df, aes(x, y, fill = grp, label = y)) +
 geom_bar(stat = "identity") +
 geom_text(aes(y = mid_y))


# Justification -------------------------------------------------------------
df <- data.frame(
  x = c(1, 1, 2, 2, 1.5),
  y = c(1, 2, 1, 2, 1.5),
  text = c("bottom-left", "bottom-right", "top-left", "top-right", "center")
)
ggplot(df, aes(x, y)) +
  geom_text(aes(label = text))

ggplot(df, aes(x, y)) +
  geom_text(aes(label = text), vjust = "inward", hjust = "inward")

# }