### Usage

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,
)


### 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.

### Examples

library(sf)