draw_legend: Calculate placement of legend and draw it

In tinyplot: Lightweight Extension of the Base R Graphics System

Calculate placement of legend and draw it

Description

Internal function used to calculate the placement of (including outside the plotting area) and drawing of legend.

Usage

draw_legend(
  legend = NULL,
  legend_args = NULL,
  by_dep = NULL,
  lgnd_labs = NULL,
  type = NULL,
  pch = NULL,
  lty = NULL,
  lwd = NULL,
  col = NULL,
  bg = NULL,
  cex = NULL,
  gradient = FALSE,
  lmar = NULL,
  has_sub = FALSE,
  new_plot = TRUE
)

Arguments

legend	Legend placement keyword or list, passed down from tinyplot.
legend_args	Additional legend arguments to be passed to legend().
by_dep	The (deparsed) "by" grouping variable name.
lgnd_labs	The labels passed to legend(legend = ...).
type	Plotting type(s), passed down from tinyplot.
pch	Plotting character(s), passed down from tinyplot.
lty	Plotting linetype(s), passed down from tinyplot.
lwd	Plotting line width(s), passed down from tinyplot.
col	Plotting colour(s), passed down from tinyplot.
bg	Plotting character background fill colour(s), passed down from tinyplot.
cex	Plotting character expansion(s), passed down from tinyplot.
gradient	Logical indicating whether a continuous gradient swatch should be used to represent the colors.
lmar	Legend margins (in lines). Should be a numeric vector of the form c(inner, outer), where the first number represents the "inner" margin between the legend and the plot, and the second number represents the "outer" margin between the legend and edge of the graphics device. If no explicit value is provided by the user, then reverts back to tpar("lmar") for which the default values are c(1.0, 0.1).
has_sub	Logical. Does the plot have a sub-caption. Only used if keyword position is "bottom!", in which case we need to bump the legend margin a bit further.
new_plot	Logical. Should we be calling plot.new internally?

Value

No return value, called for side effect of producing a(n empty) plot with a legend in the margin.

Examples

oldmar = par("mar")

draw_legend(
  legend = "right!", ## default (other options incl, "left(!)", ""bottom(!)", etc.)
  legend_args = list(title = "Key", bty = "o"),
  lgnd_labs = c("foo", "bar"),
  type = "p",
  pch = 21:22,
  col = 1:2
)

# The legend is placed in the outer margin...
box("figure", col = "cyan", lty = 4)
# ... and the plot is proportionally adjusted against the edge of this
# margin.
box("plot")
# You can add regular plot objects per normal now
plot.window(xlim = c(1,10), ylim = c(1,10))
points(1:10)
points(10:1, pch = 22, col = "red")
axis(1); axis(2)
# etc.

# Important: A side effect of draw_legend is that the inner margins have been
# adjusted. (Here: The right margin, since we called "right!" above.)
par("mar")

# To reset you should call `dev.off()` or just reset manually.
par(mar = oldmar)

# Note that the inner and outer margin of the legend itself can be set via
# the `lmar` argument. (This can also be set globally via
# `tpar(lmar = c(inner, outer))`.)
draw_legend(
  legend_args = list(title = "Key", bty = "o"),
  lgnd_labs = c("foo", "bar"),
  type = "p",
  pch = 21:22,
  col = 1:2,
  lmar = c(0, 0.1) ## set inner margin to zero
)
box("figure", col = "cyan", lty = 4)

par(mar = oldmar)

# Continuous (gradient) legends are also supported
draw_legend(
  legend = "right!",
  legend_args = list(title = "Key"),
  lgnd_labs = LETTERS[1:5],
  col = hcl.colors(5),
  gradient = TRUE ## enable gradient legend
)

par(mar = oldmar)

tinyplot documentation built on Sept. 11, 2024, 7:12 p.m.