mapmisc (version 2.1.0)

scaleBar: Scale bar and inset map

Description

Utilities for plotting a map, adding a scale bar and north arrow, and adding a legend of colour scales.

Usage

scaleBar(crs, pos = "bottomright",   
	cex=1,
    pt.cex = 1.1*cex,
    seg.len=5*cex,
    title.cex=cex,
    outer=TRUE,...)
insetMap(crs, pos="bottomright",map="osm",zoom=0, 
		width=max(c(0.2, 1-par('plt')[2])), 
		col="#FF000090", borderMap=NULL,
			cropInset = terra::ext(-180, 180,  -47, 71),
			outer=TRUE, inset = c(0.1, 0.1), ...)

Value

A list containig coordinates of the elements of the scale bar.

Arguments

crs

A character string from which a projection can be extracted with terra::crs

pos

Position, as specified in the legend function.

cex

scaling factor for the legend

pt.cex

Scaling factor north arrow (can be zero).

seg.len

approximate length (in character units) of the scale bar. can be zero.

title.cex

scaling for the distance text

outer

If TRUE, put bar or map in the margin of the plot

map

Either a Raster for the inset map or a string passed to openmap's path argument

zoom

Zoom level if retrieving inset map from openmap

width

Width of the inset map, as a fraction of the plot window

col

Colour for shaded region of inset map

borderMap

border style for the inset map (passed to polygon)

cropInset

Crop the insert map to this extent

inset

how far from the border to put the inset map

...

Additional arguments passed to legend for scaleBar or polygon (for insetMap).

Author

Patrick Brown

Details

scaleBar produces a scale bar reflecting the distance travelling on a great circle from the centre of the plot and travelling to the right. The length of the bar is the width of 6 characters times scale.cex.

Examples

Npoints = 20
set.seed(0)
myPoints = vect(
	cbind(runif(Npoints)-0.1, 51+runif(Npoints)), 
	atts=data.frame(
		y1=c(NA, rnorm(Npoints-1)), 
	    y2=c(sample(0:5, Npoints-1,replace=TRUE), NA)
	),
	crs=crsLL)



breaks = c(-100, -1, 1, Inf)
thecol = c('red','orange','blue')


oldpar = map.new(myPoints)
plot(myPoints,col = as.character(cut(
	myPoints$y1, breaks, thecol
)),add=TRUE)
scaleBar(myPoints, "bottomright",cex=1.25, seg.len=2)
legendBreaks("topleft", legend=breaks, col=thecol)

thedot = insetMap(crs=myPoints, 
	pos="bottomleft",
	 col='#00000000', lty=0, outer=FALSE, width=0.25)
points(thedot)

par(oldpar)