Spatial accessibility: FCA family, gravity access and nearest facility

FcaAccessibility: 2SFCA (Luo and Wang 2003), E2SFCA (Luo and Qi 2009, stepwise weights), KD2SFCA (weights exp(-d^power) within d0), Gaussian (Dai 2010) and 3SFCA (Wan, Zou and Sternberg 2012). GravityAccessibility: Hansen (1959) sum over j of S_j exp(-beta d_ij). NearestFacility: nearest supply site. RadiationFlows: Simini et al. (2012) radiation model.

Usage

FcaAccessibility(
  supply,
  demand,
  D,
  d0,
  method = "2SFCA",
  steps = NULL,
  power = 2
)

GravityAccessibility(supply, D, beta)

NearestFacility(D)

RadiationFlows(population, coords, outflow = NULL)

Arguments

supply

Supply at facilities.

demand

Demand populations.

D

Demand x supply distance matrix.

d0

Catchment radius.

method

FCA variant.

steps

E2SFCA list of c(upper distance, weight).

power

KD2SFCA exponent.

beta

Gravity decay.

population

Populations.

coords

Coordinates.

outflow

Total outflows (default the populations).

Value

List, vector or matrix.

References

Luo, W. and Wang, F. (2003). Measures of spatial accessibility to health care in a GIS environment. Environment and Planning B 30, 865-884.

Simini, F., Gonzalez, M. C., Maritan, A. and Barabasi, A.-L. (2012). A universal model for mobility and migration patterns. Nature 484, 96-100.

Examples

FcaAccessibility(c(10, 5), c(100, 200, 100), rbind(c(1, 5), c(2, 2), c(5, 1)), 3)$access
#> [1] 0.03333333 0.05000000 0.01666667
GravityAccessibility(c(10, 5), rbind(c(1, 5), c(2, 2)), 0.5)
#> [1] 6.475732 5.518192