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A simulated annealing algorithm to solve the max-p-region problem

Source: R/spatial_cluster.R
st_maxp_sa.Rd

A wrapper function for rgeoda::maxp_sa().The max-p-region problem is a special case of constrained clustering where a finite number of geographical areas are aggregated into the maximum number of regions (max-p-regions), such that each region is geographically connected and the clusters could maximize internal homogeneity.

Usage

st_maxp_sa(
  sfj,
  varcol,
  wt = NULL,
  boundvar,
  min_bound,
  cooling_rate = 0.85,
  sa_maxit = 1,
  iterations = 99,
  initial_regions = vector("numeric"),
  scale_method = "standardize",
  distance_method = "euclidean",
  seed = 123456789,
  cpu_threads = 6,
  rdist = numeric()
)

Arguments

sfj

An sf (simple feature) object.

varcol

The variable selected to calculate spatial lag, which is a character.

wt

(optional) The spatial weights object,which can use st_weights() to construct,default is constructed by st_weights(sfj,'contiguity').

boundvar

A numeric vector of selected bounding variable.

min_bound

A minimum value that the sum value of bounding variable int each cluster should be greater than.

cooling_rate

(optional) The cooling rate of a simulated annealing algorithm. Defaults to 0.85.

sa_maxit

(optional) The number of iterations of simulated annealing. Defaults to 1.

iterations

(optional) The number of iterations of greedy algorithm. Defaults to 99.

initial_regions

(optional) The initial regions that the local search starts with. Default is empty. means the local search starts with a random process to "grow" clusters.

scale_method

(optional) One of the scaling methods 'raw', 'standardize', 'demean', 'mad', 'range_standardize', 'range_adjust' to apply on input data. Default is 'standardize' (Z-score normalization).

distance_method

(optional) The distance method used to compute the distance betwen observation i and j. Defaults to "euclidean". Options are "euclidean" and "manhattan"

seed

(optional) The seed for random number generator. Defaults to 123456789.

cpu_threads

(optional) The number of cpu threads used for parallel computation.Default is 6.

rdist

(optional) The distance matrix (lower triangular matrix, column wise storage).

Value

A names list with names "Clusters", "Total sum of squares", "Within-cluster sum of squares", "Total within-cluster sum of squares", and "The ratio of between to total sum of squares".

Author

Wenbo Lv lyu.geosocial@gmail.com

Examples

library(sf)
guerry = read_sf(system.file("extdata", "Guerry.shp", package = "rgeoda"))
guerry_clusters = st_maxp_sa(guerry,c('Crm_prs','Crm_prp','Litercy','Donatns',
'Infants','Suicids'),boundvar = 'Pop1831',min_bound = 3236.67)
guerry_clusters
#> $Clusters
#>  [1] 2 3 7 5 5 7 3 1 6 1 7 5 8 7 4 4 2 7 3 4 7 7 6 5 8 8 4 5 1 1 1 5 4 2 2 5 3 1
#> [39] 2 7 7 4 8 1 1 5 2 2 6 6 2 6 3 4 6 2 3 3 2 3 7 1 1 1 6 6 5 6 2 2 8 8 3 8 4 3
#> [77] 1 1 5 5 4 4 4 6 3
#> 
#> $`Total sum of squares`
#> [1] 504
#> 
#> $`Within-cluster sum of squares`
#> [1] 44.78939 44.22570 24.40716 52.89492 50.78755 36.79676
#> 
#> $`Total within-cluster sum of squares`
#> [1] 250.0985
#> 
#> $`The ratio of between to total sum of squares`
#> [1] 0.4962272
#>