add_colourbar: add_colorbar

In mpadge/osmplotr: Bespoke Images of 'OpenStreetMap' Data

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 single 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 ggplot2 terms; default=3).
fontface	Fontface for colourbar labels (1:4=plain,bold,italic,bold-italic).
fontfamily	Family of colourbar font (for example, 'Times').
...	Mechanism to allow many parameters to be passed with alternative names (such as xyz for fontxyz).

Value

Modified version of map with colourbar added.

See Also

osm_basemap, add_osm_surface.

Other map-extra: add_axes(), osm_line2poly()

Examples

bbox <- get_bbox (c (-0.13, 51.5, -0.11, 51.52))
map <- 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_osm_map (map)

# Horizontal colourbar shifted away from margins:
map <- 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_osm_map (map)

mpadge/osmplotr documentation built on Oct. 28, 2024, 11:45 a.m.