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Create a Glyph Segment plot using ggplot2

Source: R/geom_glyph_segment.R
geom_glyph_segment.Rd

This function enables the creation of segment glyphs by defining major coordinates (longitude and latitude) and minor segment structures within a grid cell. Each glyph's appearance can be customized by specifying its height, width, and scaling, allowing for flexible data representation in a visual context.

Usage

geom_glyph_segment(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  x_major = NULL,
  x_minor = NULL,
  y_major = NULL,
  y_minor = NULL,
  yend_minor = NULL,
  width = "default",
  x_scale = identity,
  y_scale = identity,
  height = "default",
  global_rescale = TRUE,
  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, 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.

...

Other arguments passed on to layer(). These are often aesthetics, used to set an aesthetic to a fixed value, like colour = "red" or size = 3. They may also be parameters to the paired geom/stat.

x_major, x_minor, y_major, y_minor, yend_minor

The name of the variable (as a string) for the major and minor x and y axes. x_major and y_major specify a longitude and latitude on a map while x_minor, y_minor, and yend_minor provide the structure for glyph.

width

The width of each glyph. The `default` is set to the smallest distance between two consecutive coordinates, converted from meters to degrees of latitude using the Haversine method.

y_scale, x_scale

The scaling function to be applied to each set of minor values within a grid cell. The default is identity which produces a result without scaling.

height

The height of each glyph. The `default` is calculated using the ratio (1:1.618) relative to the `width`, to maintain a consistent aspect ratio.

global_rescale

Determines whether or not the rescaling is performed globally or separately for each individual glyph.

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.

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().

Value

a ggplot object

Examples

library(ggplot2)

# Basic glyph map with base map and custom theme
aus_temp |>
  ggplot(aes(x_major = long, y_major = lat,
         x_minor = month, y_minor = tmin, yend_minor = tmax)) +
  geom_sf(data = ozmaps::abs_ste, fill = "grey95",
          color = "white",inherit.aes = FALSE) +
  geom_glyph_segment() +
  ggthemes::theme_map()



# Adjust width and height of the glyph
aus_temp |>
  ggplot(aes(x_major = long, y_major = lat,
         x_minor = month, y_minor = tmin, yend_minor = tmax)) +
  geom_sf(data = ozmaps::abs_ste, fill = "grey95",
          color = "white",inherit.aes = FALSE) +
  geom_glyph_segment(width = rel(4.5), height = rel(3)) +
 ggthemes::theme_map()


# Extend glyph map with reference box and line
aus_temp |>
 ggplot(aes(x_major = long, y_major = lat,
         x_minor = month, y_minor = tmin, yend_minor = tmax)) +
  geom_sf(data = ozmaps::abs_ste, fill = "grey95",
          color = "white",inherit.aes = FALSE) +
  add_glyph_boxes() +
  add_ref_lines() +
  geom_glyph_segment() +
  ggthemes::theme_map()