get_dist_focus: Get distance maps

In geocausal: Causal Inference with Spatio-Temporal Data

Get distance maps

Description

'get_dist_focus()' generates a distance map from focus locations.

Usage

get_dist_focus(window, lon, lat, resolution, mile = FALSE, preprocess = FALSE)

Arguments

window	owin object
lon	vector of longitudes
lat	vector of latitudes
resolution	resolution of raster objects
mile	logical. 'mile' specifies whether to return the output in miles instead of kilometers (by default, FALSE).
preprocess	logical. 'preprocess' specifies whether to first pick the potentially closest point. It is recommended to set 'preprocess = TRUE' if users need to obtain distances from many points.

Details

'get_dist_focus()' depends on 'geosphere::distVincentyEllipsoid()'. Since it calculates accurate distances considering the ellipsoid, the process sometimes becomes computationally demanding, namely when we need to obtain distances from many points. In that case, users can set 'preprocess = TRUE'. With this option, 'get_dist_focus()' calculates distances from points by first identifying the closest point using 'sf::st_nearest_feature()' with approximations. This process is more efficient than computing distances from all the points with 'geosphere::distVincentyEllipsoid()' and then obtaining the minimum of all the distances. By default, 'get_dist_focus()' returns distances in kilometers unless users set 'mile = TRUE'.

Value

an im object

geocausal documentation built on April 3, 2025, 8:46 p.m.