Use glycan cartoons as legend labels — guide

guide_glycan() is a legend guide that replaces the usual text labels with glycan cartoons while retaining the legend keys drawn by the plot layers. Mapped discrete values and values returned by the scale's labels argument may be glycan structure strings supported by glyparse::auto_parse() or glyrepr::glycan_structure() vectors.

Usage

guide_glycan(
  title = ggplot2::waiver(),
  theme = NULL,
  position = NULL,
  direction = NULL,
  override.aes = list(),
  nrow = NULL,
  ncol = NULL,
  reverse = FALSE,
  order = 0,
  size = 0.4,
  orient = c("left", "right", "up", "down"),
  hjust = 0,
  vjust = vjust_red_end(),
  show_linkage = TRUE,
  style = style_glydraw(),
  red_end = NULL
)

Arguments

title: A character string or expression indicating a title of guide. If NULL, the title is not shown. By default (waiver()), the name of the scale object or the name specified in labs() is used for the title.
theme: A theme object to style the guide individually or differently from the plot's theme settings. The theme argument in the guide partially overrides, and is combined with, the plot's theme. Arguments that apply to a single legend are respected, most of which have the legend-prefix. Arguments that apply to combined legends (the legend box) are ignored, including legend.position, legend.justification.*, legend.location and legend.box.*.
position: A character string indicating where the legend should be placed relative to the plot panels. One of "top", "right", "bottom", "left", or "inside".
direction: A character string indicating the direction of the guide. One of "horizontal" or "vertical".
override.aes: A list specifying aesthetic parameters of legend key. See details and examples.
nrow, ncol: The desired number of rows and column of legends respectively.
reverse: logical. If TRUE the order of legends is reversed.
order: positive integer less than 99 that specifies the order of this guide among multiple guides. This controls the order in which multiple guides are displayed, not the contents of the guide itself. If 0 (default), the order is determined by a secret algorithm.
size: Positive scalar that uniformly scales each legend-label cartoon. Defaults to 0.4.
orient: Direction in which the glycan extends from its reducing end: one of "left", "right", "up", or "down". Defaults to "left".
hjust: Horizontal cartoon justification between 0 and 1, or hjust_red_end(). It defaults to 0 for horizontal cartoons and hjust_red_end() for vertical cartoons.
vjust: Vertical cartoon justification between 0 and 1, or vjust_red_end(). It defaults to vjust_red_end() for horizontal cartoons and 0.5 for vertical cartoons.
show_linkage: Whether to show glycosidic linkage annotations inside the cartoons. Defaults to TRUE.
style: A style_glydraw() object that controls the cartoons' visual appearance.
red_end: Reducing-end annotation. NULL, the default, uses red_end from style. A non-NULL value overrides style$red_end.

Value

A ggplot2 legend guide that draws glycan cartoons in place of text labels.

Examples

glycans <- data.frame(
  structure = c(
    "Gal(b1-3)GalNAc(a1-",
    "Man(a1-3)[Man(a1-6)]Man(b1-4)GlcNAc(b1-"
  ),
  abundance = c(12, 8)
)

ggplot2::ggplot(
  glycans,
  ggplot2::aes(
    x = .data$structure,
    y = .data$abundance,
    fill = .data$structure
  )
) +
  ggplot2::geom_col() +
  ggplot2::scale_fill_discrete(guide = guide_glycan())