median_center: Median Center

In centr: Weighted and Unweighted Spatial Centers

Median Center

Description

Median center iteratively calculates the point that minimizes distance to all features. One can specify the groups to calculate individual centers for and weights for each individual point. It is analagous to the ArcGIS Pro Median Center tool.

It uses the methodology introduced by Kuhn and Kuenne (1962).

Currently, median center is only implemenented for projected data.

Usage

median_center(x, group, weight, tolerance = 1e-04, ...)

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
tolerance	numeric threshold determining when an estimate improvement is sufficiently small enough to stop iterating (smaller = slower, but more precision)
...	expressions passed to dplyr::summarise()

Value

An sf object with a median center for each group

Examples

df <- data.frame(
  lon = c(-88, -90, -92, -89, -90),
  lat = c(42, 40, 30, 32, 42),
  grp = c("a", "b", "a", "b", "a"),
  wt = c(1, 1, 1, 1, 1)
)
x <- sf::st_as_sf(df, coords = c("lon", "lat"), crs = 4326)
x_transformed <- sf::st_transform(x, crs = "ESRI:102003")
median_center(x_transformed, group = "grp", weight = "wt")

x_transformed |>
  dplyr::group_by(grp) |>
  median_center(weight = "wt")

centr documentation built on June 8, 2025, 11:36 a.m.