cartogramR_options {cartogramR}

Set the options of cartogramR in the correct format

Description

Set the options of cartogramR in the correct format

Usage

cartogramR_options(
  options,
  method = c("gsm", "gn", "dcn", "GastnerSeguyMore", "GastnerNewman",
    "DougenikChrismanNiemeyer")
)

Arguments

options

a named list with some (or all) the following components:

• maxit: (all method) the maximum number of iterations, default to 50.

• absrel: (all method) boolean, if TRUE relative convergence if FALSE absolute convergence (default to TRUE)

• abserror: (all method) Areas on cartogram differ at most by an (absolute value of) error of abserror. That is, max_{polygons} |area_on_cartogram - target_area| <= abserror (default to 10000)

• abstol: ("dcn") the absolute convergence error tolerance: max_\{polygons\} |area(i) - area(i-1)| default to 1000

• relerror: (all method) Areas on cartogram differ at most by an (absolute value of) relative error of relerror. That is, max_\{polygons\} |area_on_cartogram / target_area - 1| <= relerror (default to 0.01)

• reltol: ("dcn") the absolute convergence tolerance: max_\{polygons\} abs((area(i) - area(i-1))/area(i-1) default to 1e-3

• L: (⁠"gsm" or "gn"⁠) integer, gives the value of L (default is 512), must be a power of two (for fftw)

• mp: (all method) if a region contains exactly zero population, it will be replaced by mp times the smallest (strictly) positive population in any region (default to 0.2)

• pf: (⁠"gsm" or "gn"⁠) Determines space between map and boundary (default to 1.5)

• sigma: (⁠"gsm" or "gn"⁠) Width of Gaussian blur to smoothen the density (default to 5)

• center: (⁠"gsm" or "gn"⁠) either a character string (only possible choices are "centroid" or "point_on_surface") or a function. If the object is a function, it will be used to calculate the "center" of polygons; "point_on_surface" will use the function sf::st_point_on_surface while "centroid" (the default) will use sf::st_centroid.

• verbose: (all method) integer giving the verbosity level (default to 0, not verbose)

• grid: (⁠"gsm" or "gn"⁠) boolean, if TRUE export the final grid from flow algorithm (default to TRUE). Setting to FALSE

• check.ring.dir: (all method) boolean, if TRUE controls polygons orientation (default to TRUE)

• check.only: (all method) boolean, if TRUE control only polygons orientation and no replacement is done (default to FALSE)

method

the method to be used, can be one of the following: gsm or GastnerSeguyMore (default), gn or GastnerNewman, dcn or DougenikChrismanNiemeyer.

Value

a list to be processed by cartogramR

References

• Dougenik, J., Chrisman, R. & Niemeyer, D. (1985). An algorithm to construct continuous area cartograms. Professional Geographer 37: 75-81.

• Gastner, M. & Newman, M. E. J. (2004). Diffusion-based method for producing density equalizing maps. Proc. Natl. Acad. Sci. USA, 101:7499-7504

• Gastner, M., Seguy, V. & More, P. (2018). Fast flow-based algorithm for creating density-equalizing map projections. Proceedings of the National Academy of Sciences USA, 115:E2156-E2164

Examples

  data(usa)
  carto1 <- cartogramR(usa, "electors64", options=list(verbose=1, L=256))
  plot(carto1)