geom_cnt_text: Plot label or text on centerline with ggplot2

In centerline: Extract Centerline from Closed Polygons

Plot label or text on centerline with ggplot2

Description

Binding for geomtextpath::geom_textsf() and geomtextpath::geom_labelsf()

Usage

geom_cnt_text(
  mapping = ggplot2::aes(),
  data = NULL,
  stat = "sf",
  position = "identity",
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE,
  keep = 0.5,
  method = c("voronoi", "straight"),
  simplify = TRUE,
  ...
)

geom_cnt_label(
  mapping = ggplot2::aes(),
  data = NULL,
  stat = "sf",
  position = "identity",
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE,
  keep = 0.5,
  method = c("voronoi", "straight"),
  simplify = 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, either as a ggproto Geom subclass or as a string naming the stat stripped of the stat_ prefix (e.g. "count" rather than "stat_count")
position	Position adjustment, either as a string naming the adjustment (e.g. "jitter" to use position_jitter), or the result of a call to a position adjustment function. Use the latter if you need to change the settings of the adjustment.
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. You can also set this to one of "polygon", "line", and "point" to override the default legend.
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().
keep	numeric, proportion of points to retain (0.05-5.0; default 0.5). See Details.
method	character, either "voronoi" (default) or "straight", or just the first letter "v" or "s". See Details.
simplify	logical, if TRUE (default) then the centerline will be smoothed with smoothr::smooth_ksmooth()
...	Arguments passed on to geom_textpath, geom_labelpath text_only A logical(1) indicating whether the path part should be plotted along with the text (FALSE, the default). If TRUE, any parameters or aesthetics relating to the drawing of the path will be ignored. gap A logical(1) which if TRUE, breaks the path into two sections with a gap on either side of the label. If FALSE, the path is plotted as a whole. Alternatively, if NA, the path will be broken if the string has a vjust between 0 and 1, and not otherwise. The default for the label variant is FALSE and for the text variant is NA. upright A logical(1) which if TRUE (default), inverts any text where the majority of letters would upside down along the path, to improve legibility. If FALSE, the path decides the orientation of text. halign A character(1) describing how multi-line text should be justified. Can either be "center" (default), "left" or "right". offset A unit object of length 1 to determine the offset of the text from the path. If this is NULL (default), the vjust parameter decides the offset. If not NULL, the offset argument overrules the vjust setting. parse A logical(1) which if TRUE, will coerce the labels into expressions, allowing for plotmath syntax to be used. straight A logical(1) which if TRUE, keeps the letters of a label on a straight baseline and if FALSE (default), lets individual letters follow the curve. This might be helpful for noisy paths. padding A unit object of length 1 to determine the padding between the text and the path when the gap parameter trims the path. text_smoothing a numeric(1) value between 0 and 100 that smooths the text without affecting the line portion of the geom. The default value of 0 means no smoothing is applied. rich A logical(1) whether to interpret the text as html/markdown formatted rich text. Default: FALSE. See also the rich text section of the details in geom_textpath(). label.padding Amount of padding around label. Defaults to 0.25 lines. label.r Radius of rounded corners. Defaults to 0.15 lines.

Details

Aesthetics

geom_cnt_text() understands the following aesthetics:

• x

• y

• label

• alpha

• angle

• colour

• family

• fontface

• group

• hjust

• linecolour

• lineheight

• linetype

• linewidth

• size

• spacing

• textcolour

• vjust

In addition to aforementioned aesthetics, geom_cnt_label() also understands:

• boxcolour

• boxlinetype

• boxlinewidth

• fill

See Also

geom_cnt(), geomtextpath::geom_textsf(), geomtextpath::geom_labelsf(), ggplot2::geom_sf()

Examples

library(sf)
library(ggplot2)

lake <-
  sf::st_read(
    system.file("extdata/example.gpkg", package = "centerline"),
    layer = "lake",
    quiet = TRUE
  )

# Plot centerline and lake name as text
ggplot() +
  geom_sf(data = lake) +
  geom_cnt_text(
    data = lake,
    aes(label = "Lake Ohau"),
    size = 8,
    simplify = TRUE
  ) +
theme_void()

# Plot lake name as label
ggplot() +
  geom_sf(data = lake) +
  geom_cnt_label(
    data = lake,
    aes(label = "Lake Ohau"),
    linecolor = NA, # disable line drawing
    size = 10,
    method = "s",
    simplify = TRUE
  ) +
theme_void()

centerline documentation built on Sept. 9, 2025, 5:38 p.m.