geom_text_contour: Label contours
In metR: Tools for Easier Analysis of Meteorological Fields

geom_label_contour

R Documentation

Label contours

Description

Draws labels on contours built with ggplot2::stat_contour.

Usage

geom_label_contour(
  mapping = NULL,
  data = NULL,
  stat = "text_contour",
  position = "identity",
  ...,
  min.size = 5,
  skip = 1,
  label.placer = label_placer_flattest(),
  parse = FALSE,
  nudge_x = 0,
  nudge_y = 0,
  label.padding = grid::unit(0.25, "lines"),
  label.r = grid::unit(0.15, "lines"),
  label.size = 0.25,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

geom_text_contour(
  mapping = NULL,
  data = NULL,
  stat = "text_contour",
  position = "identity",
  ...,
  min.size = 5,
  skip = 1,
  rotate = TRUE,
  label.placer = label_placer_flattest(),
  parse = FALSE,
  nudge_x = 0,
  nudge_y = 0,
  stroke = 0,
  check_overlap = FALSE,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

`mapping`	Set of aesthetic mappings created by `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. A `function` can be created from a `formula` (e.g. `~ head(.x, 10)`).
`stat`	The statistical transformation to use on the data for this layer. When using a `⁠geom_*()⁠` function to construct a layer, the `stat` argument can be used to override the default coupling between geoms and stats. The `stat` argument accepts the following: A `Stat` ggproto subclass, for example `StatCount`. A string naming the stat. To give the stat as a string, strip the function name of the `stat_` prefix. For example, to use `stat_count()`, give the stat as `"count"`. For more information and other ways to specify the stat, see the layer stat documentation.
`position`	A position adjustment to use on the data for this layer. This can be used in various ways, including to prevent overplotting and improving the display. The `position` argument accepts the following: The result of calling a position function, such as `position_jitter()`. This method allows for passing extra arguments to the position. A string naming the position adjustment. To give the position as a string, strip the function name of the `position_` prefix. For example, to use `position_jitter()`, give the position as `"jitter"`. For more information and other ways to specify the position, see the layer position documentation.
`...`	Other arguments passed on to `layer()`'s `params` argument. These arguments broadly fall into one of 4 categories below. Notably, further arguments to the `position` argument, or aesthetics that are required can not be passed through `...`. Unknown arguments that are not part of the 4 categories below are ignored. Static aesthetics that are not mapped to a scale, but are at a fixed value and apply to the layer as a whole. For example, `colour = "red"` or `linewidth = 3`. The geom's documentation has an Aesthetics section that lists the available options. The 'required' aesthetics cannot be passed on to the `params`. Please note that while passing unmapped aesthetics as vectors is technically possible, the order and required length is not guaranteed to be parallel to the input data. When constructing a layer using a `⁠stat_()⁠` function, the `...` argument can be used to pass on parameters to the `geom` part of the layer. An example of this is `stat_density(geom = "area", outline.type = "both")`. The geom's documentation lists which parameters it can accept. Inversely, when constructing a layer using a `⁠geom_()⁠` function, the `...` argument can be used to pass on parameters to the `stat` part of the layer. An example of this is `geom_area(stat = "density", adjust = 0.5)`. The stat's documentation lists which parameters it can accept. The `key_glyph` argument of `layer()` may also be passed on through `...`. This can be one of the functions described as key glyphs, to change the display of the layer in the legend.
`min.size`	minimum number of points for a contour to be labelled.
`skip`	number of contours to skip
`label.placer`	a label placer function. See `label_placer_flattest()`.
`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. Cannot be jointly specified with `position`.
`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`	Replaced by the `linewidth` aesthetic. Size of label border, in mm.
`na.rm`	If `FALSE`, the default, missing values are removed with a warning. If `TRUE`, missing values are silently removed.
`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. It can also be a named logical vector to finely select the aesthetics to display. To include legend keys for all levels, even when no data exists, use `TRUE`. If `NA`, all levels are shown in legend, but unobserved levels are omitted.
`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. `annotation_borders()`.
`rotate`	logical indicating whether to rotate text following the contour.
`stroke`	numerical indicating width of stroke relative to the size of the text. Ignored if less than zero.
`check_overlap`	If `TRUE`, text that overlaps previous text in the same layer will not be plotted. `check_overlap` happens at draw time and in the order of the data. Therefore data should be arranged by the label column before calling `geom_text()`. Note that this argument is not supported by `geom_label()`.

Details

Is best used with a previous call to ggplot2::stat_contour with the same parameters (e.g. the same binwidth, breaks, or bins). Note that while geom_text_contour() can angle itself to follow the contour, this is not the case with geom_label_contour().

Aesthetics

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

x
y
label
alpha
angle
colour
stroke.color
family
fontface
group
hjust
lineheight
size
vjust

Examples



library(ggplot2)
v <- reshape2::melt(volcano)
g <- ggplot(v, aes(Var1, Var2)) +
       geom_contour(aes(z = value))
g + geom_text_contour(aes(z = value))

g + geom_text_contour(aes(z = value), stroke = 0.2)

g + geom_text_contour(aes(z = value), stroke = 0.2, stroke.colour = "red")

g + geom_text_contour(aes(z = value, stroke.colour = after_stat(level)), stroke = 0.2) +
    scale_colour_gradient(aesthetics = "stroke.colour", guide = "none")

g + geom_text_contour(aes(z = value), rotate = FALSE)

g + geom_text_contour(aes(z = value),
                      label.placer = label_placer_random())

g + geom_text_contour(aes(z = value),
                      label.placer = label_placer_n(3))

g + geom_text_contour(aes(z = value),
                      label.placer = label_placer_flattest())

g + geom_text_contour(aes(z = value),
                      label.placer = label_placer_flattest(ref_angle = 90))

metR documentation built on Oct. 8, 2026, 9:17 a.m.