cartogram (version 0.2.0)

cartogram_dorling: Calculate Non-Overlapping Circles Cartogram

Description

Construct a cartogram which represents each geographic region as non-overlapping circles (Dorling 1996).

Usage

cartogram_dorling(x, weight, k = 5, m_weight = 1, itermax = 1000)
# S3 method for sf
cartogram_dorling(x, weight, k = 5, m_weight = 1, itermax = 1000)
# S3 method for SpatialPolygonsDataFrame
cartogram_dorling(x, weight, k = 5, m_weight = 1, itermax = 1000)

Arguments

x

SpatialPolygonsDataFrame, SpatialPointsDataFrame or an sf object

weight

Name of the weighting variable in x

k

Share of the bounding box of x filled by the larger circle

m_weight

Circles' movements weights. An optional vector of numeric weights (0 to 1 inclusive) to apply to the distance each circle moves during pair-repulsion. A weight of 0 prevents any movement. A weight of 1 gives the default movement distance. A single value can be supplied for uniform weights. A vector with length less than the number of circles will be silently extended by repeating the final value. Any values outside the range [0, 1] will be clamped to 0 or 1.

itermax

Maximum iterations for the cartogram transformation.

Value

Non overlaping proportional circles of the same class as x.

References

Dorling, D. (1996). Area Cartograms: Their Use and Creation. In Concepts and Techniques in Modern Geography (CATMOG), 59.

Examples

# NOT RUN {
library(maptools)
library(cartogram)
library(rgdal)
data(wrld_simpl)

# Remove uninhabited regions
afr <- spTransform(wrld_simpl[wrld_simpl$REGION==2 & wrld_simpl$POP2005 > 0,], 
                   CRS("+init=epsg:3395"))

# Create cartogram
afr_carto <- cartogram_dorling(afr, "POP2005")

# Plot 
par(mfcol=c(1,2))
plot(afr, main="original")

plot(afr, main="distorted (sp)")
plot(afr_carto, col = "red", add=TRUE)

# Same with sf objects
library(sf)

afr_sf = st_as_sf(afr)

afr_sf_carto <- cartogram_dorling(afr_sf, "POP2005")

# Plot 
par(mfcol=c(1,3))
plot(afr, main="original")
plot(afr_carto, main="distorted (sp)")
plot(st_geometry(afr_sf_carto), main="distorted (sf)")
# }