Mean Center

Mean center calculates the geographic average center. One can specify the groups to calculate individual centers for groups and weights for each individual point. It is analagous to the ArcGIS Pro Mean Center tool.

If st_is_longlat(x), mean center is calculated assuming a spherical Earth. Projected data is calculated assuming a "flat" Earth.

Usage

mean_center(x, group, weight, ...)

Arguments

x

Input POINT or POLYGON simple features

group

column name(s) specifying groups to calculate individual mean centers for

weight

name of numeric weight column specifying an individual point's contribution to the mean center

...

expressions passed to dplyr::summarise()

Value

An sf object with a mean center for each group

Examples

df <- data.frame(
  lon = c(20, 50, 30, 80, 10),
  lat = c(25, 70, 30, 50, 30),
  grp = c("a", "b", "a", "b", "a"),
  wt = c(1, 5, 1, 3, 2)
)
x <- sf::st_as_sf(df, coords = c("lon", "lat"), crs = 4326)
mean_center(x, group = "grp", weight = "wt")
#> Simple feature collection with 2 features and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 17.51482 ymin: 29.00224 xmax: 65.92087 ymax: 63.32603
#> Geodetic CRS:  WGS 84
#> # A tibble: 2 × 2
#>   grp              geometry
#>   <chr>         <POINT [°]>
#> 1 a     (17.51482 29.00224)
#> 2 b     (65.92087 63.32603)

x |>
  dplyr::group_by(grp) |>
  mean_center(weight = "wt")
#> Simple feature collection with 2 features and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 17.51482 ymin: 29.00224 xmax: 65.92087 ymax: 63.32603
#> Geodetic CRS:  WGS 84
#> # A tibble: 2 × 2
#>   grp              geometry
#>   <chr>         <POINT [°]>
#> 1 a     (17.51482 29.00224)
#> 2 b     (65.92087 63.32603)