mf_legend function

Plot a legend

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().

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

Returns

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))