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centr

A Package for Weighted and Unweighted Spatial Centers

Installation

# Install centr from CRANinstall.packages("centr")# Or the development version from GitHub:# install.packages("devtools")devtools::install_github("ryanzomorrodi/centr")

Usage

The main functions aremean_center andmedian_center. They weredesigned for calculation of population weighted centroids, but can beextended to other forms of analyses.

Mean center calculates the geographic average center. One can specifythe groups to calculate individual centers for groups and weights foreach individual point. It is analagous to theArcGIS Pro MeanCentertool.

library(centr)df<-data.frame(lon= c(20,50,30,80,10),lat= c(25,70,30,50,30),group1= c("a","b","a","b","a"),group2= c(1,1,1,1,2),wt= c(1,5,1,3,2))x<-sf::st_as_sf(df,coords= c("lon","lat"),crs=4326)mean_center(x,group= c("group1","group2"),weight="wt")#> Simple feature collection with 3 features and 2 fields#> Geometry type: POINT#> Dimension:     XY#> Bounding box:  xmin: 10 ymin: 27.58952 xmax: 65.92087 ymax: 63.32603#> Geodetic CRS:  WGS 84#> # A tibble: 3 × 3#> # Groups:   group1 [2]#>   group1 group2            geometry#> * <chr>   <dbl>         <POINT [°]>#> 1 a           1 (24.88607 27.58952)#> 2 a           2             (10 30)#> 3 b           1 (65.92087 63.32603)

Median center iteratively calculates the point that minimizes distanceto all features. One can specify the groups to calculate individualcenters for and weights for each individual point. It is analagous totheArcGIS Pro MedianCentertool.

median_center(x,group= c("group1","group2"),weight="wt")#> Simple feature collection with 3 features and 2 fields#> Geometry type: POINT#> Dimension:     XY#> Bounding box:  xmin: 10 ymin: 27.96116 xmax: 50 ymax: 70#> Geodetic CRS:  WGS 84#> # A tibble: 3 × 3#> # Groups:   group1 [2]#>   group1 group2            geometry#> * <chr>   <dbl>         <POINT [°]>#> 1 a           1 (25.63316 27.96116)#> 2 a           2             (10 30)#> 3 b           1             (50 70)

Summaries of other attributes can be calculated by passing the summaryexpressions to... just as indplyr::summarise().

mean_center(x,group= c("group1","group2"),weight="wt",total_weight= sum(wt))#> Simple feature collection with 3 features and 3 fields#> Geometry type: POINT#> Dimension:     XY#> Bounding box:  xmin: 10 ymin: 27.58952 xmax: 65.92087 ymax: 63.32603#> Geodetic CRS:  WGS 84#> # A tibble: 3 × 4#> # Groups:   group1 [2]#>   group1 group2            geometry total_weight#> * <chr>   <dbl>         <POINT [°]>        <dbl>#> 1 a           1 (24.88607 27.58952)            2#> 2 a           2             (10 30)            2#> 3 b           1 (65.92087 63.32603)            8