cartogram_dorling: Calculate Non-Overlapping Circles Cartogram

In cartogram: Create Cartograms with R

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 class 'sf'
cartogram_dorling(x, weight, k = 5, m_weight = 1, itermax = 1000)

## S3 method for class '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

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)")

cartogram documentation built on Aug. 27, 2020, 1:10 a.m.