Plot a layer of graduated links. Links are plotted according to discrete classes of widths.

gradLinkLayer(
  x,
  df,
  xid = NULL,
  dfid = NULL,
  var,
  breaks = getBreaks(v = df[, var], nclass = 4, method = "quantile"),
  lwd = c(1, 2, 4, 6),
  col = "red",
  legend.pos = "bottomleft",
  legend.title.txt = var,
  legend.title.cex = 0.8,
  legend.values.cex = 0.6,
  legend.values.rnd = 0,
  legend.frame = FALSE,
  add = TRUE
)

Arguments

x

an sf object, a simple feature collection.

df

a data frame that contains identifiers of starting and ending points and a variable.

xid

names of the identifier variables in x, character vector of length 2, default to the 2 first columns. (optional)

dfid

names of the identifier variables in df, character vector of length 2, default to the two first columns. (optional)

var

name of the variable used to plot the links widths.

breaks

break values in sorted order to indicate the intervals for assigning the lines widths.

lwd

vector of widths (classes of widths).

col

color of the links.

legend.pos

position of the legend, one of "topleft", "top", "topright", "right", "bottomright", "bottom", "bottomleft", "left" or a vector of two coordinates in map units (c(x, y)). If legend.pos is "n" then the legend is not plotted.

legend.title.txt

title of the legend.

legend.title.cex

size of the legend title.

legend.values.cex

size of the values in the legend.

legend.values.rnd

number of decimal places of the values displayed in the legend.

legend.frame

whether to add a frame to the legend (TRUE) or not (FALSE).

add

whether to add the layer to an existing plot (TRUE) or not (FALSE).

Note

Unlike most of cartography functions, identifiers fields are mandatory.

See also

Examples

library(sf) mtq <- st_read(system.file("gpkg/mtq.gpkg", package="cartography"))
#> Reading layer `mtq' from data source #> `/tmp/RtmppBiN3A/temp_libpath43d97684eada/cartography/gpkg/mtq.gpkg' #> using driver `GPKG' #> Simple feature collection with 34 features and 7 fields #> Geometry type: MULTIPOLYGON #> Dimension: XY #> Bounding box: xmin: 690574 ymin: 1592536 xmax: 735940.2 ymax: 1645660 #> Projected CRS: WGS 84 / UTM zone 20N
mob <- read.csv(system.file("csv/mob.csv", package="cartography")) # Create a link layer - work mobilities to Fort-de-France (97209) mob.sf <- getLinkLayer(x = mtq, df = mob[mob$j==97209,], dfid = c("i", "j")) # Plot the links - Work mobility plot(st_geometry(mtq), col = "grey60",border = "grey20")
gradLinkLayer(x = mob.sf, df = mob, legend.pos = "topright", var = "fij", breaks = c(109,500,1000,2000,4679), lwd = c(1,2,4,10), col = "#92000090", add = TRUE)