Annotate panel gridlines

Draws gridlines at specified positions, with style defaults taken from the panel.grid.major element of the set theme. Crop bounds (xmin, xmax, ymin, ymax) both filter which lines are drawn and control how far they run across the panel.

Usage

panel_grid(
  xintercept = NULL,
  yintercept = NULL,
  xmin = -Inf,
  xmax = Inf,
  ymin = -Inf,
  ymax = Inf,
  colour = NULL,
  linewidth = NULL,
  linetype = NULL,
  layout = NULL
)

Arguments

xintercept

One or more x positions for vertical gridlines, in data coordinates or wrapped in I() for normalised panel coordinates (npc). May be a vector.

yintercept

One or more y positions for horizontal gridlines, in data coordinates or wrapped in I() for normalised panel coordinates (npc). May be a vector.

xmin, xmax

Left and right crop bounds. Vertical gridlines outside [xmin, xmax] are not drawn; horizontal gridlines run only from xmin to xmax. Defaults to -Inf and Inf (full panel). Use I() for normalised coordinates (npc). Note: filtering (removing lines outside the range) only works when both the crop bound and the intercept are in data coordinates. npc bounds affect extent only.

ymin, ymax

Bottom and top crop bounds. Horizontal gridlines outside [ymin, ymax] are not drawn; vertical gridlines run only from ymin to ymax. Defaults to -Inf and Inf (full panel). Use I() for normalised coordinates (npc). Note: filtering only works when both the crop bound and the intercept are in data coordinates. npc bounds affect extent only.

colour

Inherits from panel.grid.major in the set theme. May be a vector the same length as the total number of lines.

linewidth

Inherits from panel.grid.major in the set theme. Supports rel(). May be a vector the same length as the total number of lines.

linetype

Inherits from panel.grid.major in the set theme. May be a vector the same length as the total number of lines.

layout

Controls which panels the annotation appears in. NULL (default) repeats in all panels. An integer targets a specific panel. "fixed" repeats in all panels ignoring faceting variables. See ggplot2::layer() for full details.

Value

A list of ggplot2 annotation layers.

See also

axis_line(), reference_line(), panel_background()