osmplotr (version 0.2.0)

add_colourbar: add_colorbar

Description

Adds a colourbar to an existing map. Intended to be used in combination with add_osm_surface (). At present, only plots on right side of map.

Usage

add_colourbar(map, barwidth = 0.02, barlength = 0.7, zlims, cols,
  vertical = TRUE, alpha = 0.4, text_col = "black", fontsize = 3,
  fontface, fontfamily)

Arguments

map

A ggplot2 object to which the colourbar is to be added

barwidth

Relative width of the bar (perpendicular to its direction), either a single number giving distance from right or upper margin, or two numbers giving left/right or lower/upper limits.

barlength

Relative length of the bar (parallel to its direction), either a signle number giving total length of centred bar, or two numbers giving lower/upper or left/right limits.

zlims

Vector of (min,max) values for scale of colourbar. These should be the values returned from add_osm_surface ().

cols

Vector of colours

vertical

If FALSE, colourbar is aligned horizontally instead of default vertical alignment

alpha

Transparency level of region immediately surrounding colourbar, including behind text. Lower values are more transparent.

text_col

Colour of text, tick marks, and lines on colourbar

fontsize

Size of text labels (in ggplot terms; default=3)

fontface

Fontface for colourbar labels (1:4=plain,bold,italic,bold-italic)

fontfamily

Family of colourbar font (for example, 'Times')

Value

• Modified version of map with colourbar added

See Also

plot_osm_basemap, add_osm_surface.

Examples

bbox <- get_bbox (c (-0.13, 51.5, -0.11, 51.52))
map <- plot_osm_basemap (bbox=bbox, bg="gray20")
# Align volcano data to lat-lon range of bbox
dv <- dim (volcano)
x <- seq (bbox [1,1], bbox [1,2], length.out=dv [1])
y <- seq (bbox [2,1], bbox [2,2], length.out=dv [2])
dat <- data.frame (
                  x=rep (x, dv [2]),
                  y=rep (y, each=dv [1]),
                  z=as.numeric (volcano)
                  )
map <- add_osm_surface (map, obj=london$dat_BNR, dat=dat,
                        cols=heat.colors (30))
map <- add_axes (map)
# Note colours of colourbar can be artibrarily set, and need not equal those
# passed to 'add_osm_surface'
map <- add_colourbar (map, zlims=range (volcano), cols=heat.colors(100),
                      text_col="black")
print (map)

# Horizontal colourbar shifted away from margins:
map <- plot_osm_basemap (bbox=bbox, bg="gray20")
map <- add_osm_surface (map, obj=london$dat_BNR, dat=dat,
                        cols=heat.colors (30))
map <- add_colourbar (map, zlims=range (volcano), cols=heat.colors(100),
                      barwidth=c(0.1,0.15), barlength=c(0.5, 0.9), vertical=FALSE)
print (map)