lineLabel

0th

Percentile

Line label placement with spplot and lattice.

The lineLabel function produces and draws text grobs following the paths defined by a list of Line objects. The sp.lineLabel methods use this function to work easily with spplot.

Usage
lineLabel(line, label,
          spar=.6, position = c('above', 'below'),
          textloc = 'constantSlope',
          col = add.text$col,
          alpha = add.text$alpha,
          cex = add.text$cex,
          lineheight = add.text$lineheight,
          font = add.text$font,
          fontfamily = add.text$fontfamily,
          fontface = add.text$fontface,
          lty = add.line$lty,
          lwd = add.line$lwd, 
          col.line = add.line$col,
          identifier = 'lineLabel',
          ...)

sp.lineLabel(object, labels, byid=TRUE,...)

label(object, text, ...)

Arguments
line
a list of Lines.
object
A Lines or SpatialLines object.
label, labels, text
a string or expression to be printed following the path of line. The names of labels should match the values of the ID slot of the lines to label. If labels is missing, the
byid
If TRUE (default) only the longest line of each unique ID value will be labelled.
textloc
a character or a numeric. It may be 'constantSlope', 'minSlope' or 'maxDepth', or the numeric index of the location. If it is a numeric, its length must coincide with the number of Lines.
spar
smoothing parameter. With values near zero, the label will closely follow the line. Default value is .6. See smooth.spline for details.
position
character string ('above' or 'below') to define where the text must be placed.
col, alpha, cex, lineheight, font, fontfamily, fontface
graphical arguments for the text. See gpar for details.
lty, lwd, col.line
graphical parameters for the line. See gpar for details.
identifier
A character string to identify the grob to be created.
...
other arguments
Details

Part of the label location code is adapted from panel.levelplot. smooth.spline is used to resample the segment of the line where the label is placed.

See Also

spplot sp.pointLabel pointLabel panel.levelplot smooth.spline

Aliases
  • lineLabel
  • sp.lineLabel
  • label
  • sp.lineLabel-methods
  • label-methods
  • sp.lineLabel,Lines-method
  • sp.lineLabel,SpatialLines-method
  • label,SpatialLines-method
Examples
data(meuse.grid)
coordinates(meuse.grid) = ~x+y
proj4string(meuse.grid) <- CRS("+init=epsg:28992")
gridded(meuse.grid) = TRUE

data(meuse)
coordinates(meuse) = ~x+y
data(meuse.riv)
meuse.sl <- SpatialLines(list(Lines(list(Line(meuse.riv)), "1")))

library(RColorBrewer)
myCols <- adjustcolor(colorRampPalette(brewer.pal(n=9, 'Reds'))(100), .85)

labs <- label(meuse.sl, 'Meuse River')

## Maximum depth
sl1 <- list('sp.lineLabel', meuse.sl, label=labs,
            position='below', textloc='maxDepth',
            spar=.2,
            col='darkblue', cex=1,
            fontfamily='Palatino',
            fontface=2)

spplot(meuse.grid["dist"],
       col.regions=myCols, 
       sp.layout = sl1)

## Constant slope
sl2 <- modifyList(sl1, list(textloc = 'constantSlope')) ## Default

spplot(meuse.grid["dist"],
       col.regions=myCols, 
       sp.layout = sl2)

## Location defined by its numeric index
sl3 <- modifyList(sl1, list(textloc = 140, position='above'))

spplot(meuse.grid["dist"],
       col.regions=myCols, 
       sp.layout = sl3)
Documentation reproduced from package maptools, version 0.8-26, License: GPL (>= 2)

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