gsClusterDetect (version 1.0.0)

create_dist_list: Generalized distance list as sparse list

Description

This function is an alternative to the package functions that create a square distance matrix of dimension N, with all pairwise distances. In this approach a list of named vectors is returned, where there is one element in the list for each location, and each named vector holds the distance within `threshold` of the location.

Usage

create_dist_list(
  level,
  threshold,
  st = NULL,
  county = NULL,
  unit = c("miles", "kilometers", "meters")
)

Value

a named list, where each element, named by a target location, is a named vector of distances that are within `threshold` `units` of the target.

Arguments

level

string either "county", "zip", or "tract"

threshold

numeric value; include in each location-specific named vector only those locations that a within `threshold` distance units of the target. Reasonable thresholds might be 50 (miles), 15 (miles) and 3 (miles) for county, zip, and tract, respectively, but these can be adjusted. Note if a different unit other than miles is used, then the user should also adjust this parameter appropriately

st

string; optional to specify a state; if NULL distances are returned for all zip codes or counties in the US

county

string vector of 3-fips to restrict within st; ignored unless level is "tract"

unit

string one of miles (default), kilometers, or meters; this is the unit relevant to the threshold

Examples

create_dist_list(
  level = "tract",
  threshold = 3,
  st = "MD"
)
create_dist_list(
  level = "county",
  threshold = 50,
  st = "CA",
  unit = "kilometers"
)