autolegend {paletteknife}

Add Auto-Generated Legend

Description

Add a legend for the last autocol() set generated

Usage

autolegend(...)

Arguments

...

Arguments passed directly to legend – legend text and colours are taken automatically from options('autolegend'). See examples for useful parameters, including pch and pt.cex

Details

If no location (such as 'top', 'above', or an x,y coordinate) is given, then it calls the locator() crosshairs so the position of the legend can be picked interactively. All arguments are passed to legend(), see ?legend for a full list.

Positions 'above' and 'below' are allowed which shorthand for inset and horizontal (see example).

Legend labels and fill are generated by either autopal() or autocol() and stored in the global options('autolegend') where they can be manipulated if needs be.

See more examples in ?autocol for a plot() and autolegend() work flow.

Value

No return value (NULL)

Examples

# Simplest version: click-to-draw with locator()
plot(1:10, pch=16, col=autocol(1:10, 'Blues', legend_len=5))
# autolegend() # Try me! And click on plot to add legend

# Other neat versions -- note ?legend
autolegend('above', title='Above plot')
# Exactly equivalent to...
autolegend('bottom', inset=1, horiz=TRUE, bty='n')
autolegend(x=6, y=4, ncol=2, title='Draw at (6,4)')
autolegend('topleft', title='"topleft"', ncol=2, bty='n')

# Use pch (and optionally pt.cex) in legend -- these get recycled
autolegend('bottom', horiz=TRUE, pch=16, pt.cex=3, title='pch=16, pt.cex=3')
autolegend('right', pch=1:10, pt.cex=2, title='pch=1:10')

# Manipulate the legend text, for example with format(), this is a bit long-winded!
heatmap(as.matrix(eurodist), col=autopal('turbo', limits=range(eurodist)) )
current_legend = options('autolegend')[[1]]
options(autolegend = list(format(current_legend[[1]], big.mark=','), current_legend[[2]]))
autolegend('bottom', inset=1, horiz=TRUE, title='Misleading miles between cities')

# No helper exists yet for creating size or shape legends -- follow this idea...
with(airquality, plot(Temp, pch=16, cex=Solar.R/100, col=autocol(Ozone, set='Reds')))
cex_legend = pretty(airquality$Solar.R)
legend('bottom', pt.cex=cex_legend/100, legend=cex_legend, pch=1,
  horiz=TRUE, title='Solar.R', bty='n' )
autolegend('above', title='Ozone')