cartography (version 2.1.2)

getGridLayer: Build a Regular Grid Layer

Description

Build a regular grid based on an sf object or a SpatialPolygonsDataFrame.

Usage

getGridLayer(x, cellsize, type = "regular", var, spdf, spdfid = NULL)

Arguments

x

an sf object, a simple feature collection or a SpatialPolygonsDataFrame.

cellsize

targeted area of the cell, in map units.

type

shape of the cell, "regular" for squares, "hexagonal" for hexagons.

var

name of the numeric field(s) in x to adapt to the grid (a vector).

spdf

deprecated, a SpatialPolygonsDataFrame.

spdfid

deprecated, identifier field in spdf, default to the first column of the spdf data frame. (optional)

Value

A grid is returned as an sf object.

Examples

# NOT RUN {
library(sf)
mtq <- st_read(system.file("shape/martinique.shp", package="cartography"))
# Plot dentsity of population 
mtq$dens <- mtq$P13_POP / (st_area(mtq) / (1000 * 1000)) 
bks <- getBreaks(v = mtq$dens, method = "q6")
cols <- carto.pal(pal1 = "taupe.pal", n1 = 6)
opar <- par(mfrow = c(1,2), mar = c(0,0,0,0))
choroLayer(x = mtq, var = "dens", breaks = bks, 
           border = "burlywood3", col = cols, 
           legend.pos = "topright", legend.values.rnd = 1,
           legend.title.txt = "Population density")

mygrid <- getGridLayer(x = mtq, cellsize = 3000 * 3000, 
                       type = "regular", var = "P13_POP")
## conversion from square meter to square kilometers
mygrid$densitykm <- mygrid$P13_POP / (mygrid$gridarea / (1000 * 1000)) 
choroLayer(x = mygrid, var = "densitykm", breaks = bks,
           border = "burlywood3", col = cols, 
           legend.pos = "n", legend.values.rnd = 1,
           legend.title.txt = "Population density")
plot(st_geometry(mtq), lwd = 0.2, add=TRUE, border = "#ffffff75")

# }
# NOT RUN {
library(sp)
data(nuts2006)
nuts2.spdf@data = nuts2.df
mygrid <- getGridLayer(x = nuts2.spdf, cellsize = 200000 * 200000, 
                       type = "regular", var = "pop2008")
# Plot total population
plot(st_geometry(mygrid), col="#CCCCCC",border="white")
propSymbolsLayer(x = mygrid, var = "pop2008", border = "white",
                 legend.style = "e", legend.pos = "right", 
                 legend.title.txt = "Total population",
                 inches = 0.1, col = "black", add = TRUE)

# Plot dentsity of population 
## conversion from square meter to square kilometers
mygrid$densitykm <- mygrid$pop2008 * 1000 * 1000 / mygrid$gridarea 
cols <- carto.pal(pal1 = "taupe.pal", n1 = 6)
choroLayer(x = mygrid, var = "densitykm", 
           border = "grey80",col = cols, method = "q6", 
           legend.pos = "right", legend.values.rnd = 1,
           legend.title.txt = "Population density")
par(opar)
# }