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Plot a legend

Source: R/mf_legend.R
mf_legend.Rd

Plot different types of legend. The "type" argument defines the legend type. Please note that some arguments are available for all types of legend and some others are only relevant for specific legend types (see Details). mf_legend() is a wrapper for maplegend::leg().

Usage

mf_legend(
  type,
  val,
  pos = "left",
  pal = "Inferno",
  alpha = 1,
  col = "tomato4",
  inches = 0.3,
  symbol = "circle",
  self_adjust = FALSE,
  lwd = 0.7,
  border = "#333333",
  pch = seq_along(val),
  cex = rep(1, length(val)),
  title = "Legend Title",
  title_cex = 0.8 * size,
  val_cex = 0.6 * size,
  val_rnd = 0,
  col_na = "white",
  cex_na = 1,
  pch_na = 4,
  no_data = FALSE,
  no_data_txt = "No Data",
  box_border = "#333333",
  box_cex = c(1, 1),
  horiz = FALSE,
  frame_border,
  frame = FALSE,
  bg,
  fg,
  size = 1,
  return_bbox = FALSE,
  adj = c(0, 0),
  pt_pch,
  pt_cex,
  pt_cex_na,
  pt_pch_na
)

Arguments

type

type of legend:

  • prop for proportional symbols,

  • choro for choropleth maps,

  • cont for continuous maps (e.g. raster),

  • typo for typology maps,

  • symb for symbols maps,

  • prop_line for proportional lines maps,

  • grad_line for graduated lines maps.

val

vector of value(s) (for "prop" and "prop_line", at least c(min, max) for "cont"), vector of categories (for "symb" and "typo"), break labels (for "choro" and "grad_line").

pos

position of the legend. It can be one of 'topleft', 'top', 'topright', 'right', 'bottomright', 'bottom','bottomleft', 'left', 'interactive' or a vector of two coordinates in map units (c(x, y)).

pal

a color palette name or a vector of colors

alpha

if pal is a hcl.colors palette name, the alpha-transparency level in the range [0,1]

col

color of the symbols (for "prop") or color of the lines (for "prop_line" and "grad_line")

inches

size of the largest symbol (radius for circles, half width for squares) in inches

symbol

type of symbols, 'circle' or 'square'

self_adjust

if TRUE values are self-adjusted to keep min, max and intermediate rounded values

lwd

width(s) of the symbols borders (for "prop" and "symb"), width of the largest line (for "prop_line"), vector of line width (for "grad_line")

border

symbol border color(s)

pch

type(s) of the symbols (0:25)

cex

size(s) of the symbols

title

title of the legend

title_cex

size of the legend title

val_cex

size of the values in the legend

val_rnd

number of decimal places of the values in the legend

col_na

color for missing values

cex_na

size of the symbols for missing values

pch_na

type of the symbols for missing values

no_data

if TRUE a "missing value" box is plotted

no_data_txt

label for missing values

box_border

border color of legend boxes

box_cex

width and height size expansion of boxes, (or offset between circles for "prop" legends with horiz = TRUE)

horiz

if TRUE plot an horizontal legend

frame_border

border color of the frame

frame

if TRUE the legend is plotted within a frame

bg

background color of the legend

fg

foreground color of the legend

size

size of the legend; 2 means two times bigger

return_bbox

return only bounding box of the legend. No legend is plotted.

adj

adjust the postion of the legend in x and y directions

pt_pch

deprecated

pt_cex

deprecated

pt_cex_na

deprecated

pt_pch_na

deprecated

Value

No value is returned, a legend is displayed (except if return_bbox is used).

Details

Some arguments are available for all types of legend: val, pos, title, title_cex, val_cex, frame, bg, fg, size, adj, return_bbox).

Relevant arguments for each specific legend types:

  • mf_legend(type = "prop", val, inches, symbol, col, lwd, border, val_rnd, self_adjust, horiz)

  • mf_legend(type = "choro", val, pal, val_rnd, col_na, no_data, no_data_txt, box_border, horiz)

  • mf_legend(type = "cont", val, pal, val_rnd, col_na, no_data, no_data_txt, box_border, horiz)

  • mf_legend(type = "typo", val, pal, col_na, no_data, no_data_txt, box_border)

  • mf_legend(type = "symb", val, pal, pch, cex, lwd, pch_na, cex_na, col_na, no_data, no_data_txt)

  • mf_legend(type = "prop_line", val, col, lwd, val_rnd)

  • mf_legend(type = "grad_line", val, col, lwd, val_rnd)

Examples

mtq <- mf_get_mtq()
mf_map(mtq)
mf_legend(type = "prop", pos = "topright", val = c(1, 5, 10), inches = .3)
mf_legend(
  type = "choro", pos = "bottomright", val = c(10, 20, 30, 40, 50),
  pal = hcl.colors(4, "Reds 2")
)
mf_legend(
  type = "typo", pos = "topleft", val = c("A", "B", "C", "D"),
  pal = hcl.colors(4, "Dynamic")
)
mf_legend(
  type = "symb", pos = "bottomleft", val = c("A", "B", "C"),
  pch = 21:23, cex = c(1, 2, 2),
  pal = hcl.colors(3, "Dynamic")
)
mf_legend(
  type = "grad_line", pos = "top", val = c(1, 2, 3, 4, 10, 15),
  lwd = c(0.2, 2, 4, 5, 10)
)
mf_legend(type = "prop_line", pos = "bottom", lwd = 20, val = c(5, 50, 100))