dist_wlatlng_cpp: dist_wlatlng_cpp

In gyang274/skm: Selective k-Means

Description

calculate distance between coordinate1<lat1, lng1> and coordinate2<lat2, lng2>

Usage

dist_wlatlng_mi_cpp(lat1, lng1, lat2, lng2)

dist_wlatlng_km_cpp(lat1, lng1, lat2, lng2)

distSgl_wlatlng_cpp(lat1, lng1, lat2, lng2, measure = "mi")

distRpl_wlatlng_cpp(lat1, lng1, lat2, lng2, measure = "mi",
  distRpl_GS = 100L)

Arguments

lat1	latitude of coordinate1
lng1	longitude of coordinate1
lat2	latitude of coordinate2
lng2	longitude of coordinate2
measure	"mi" (mile) or "km" (kilometer)
distRpl_GS	The grain size of a parallel algorithm sets a minimum chunk size for parallelization. In other words, at what point to stop processing input on separate threads (as sometimes creating more threads can degrade the performance of an algorithm by introducing excessive synchronization overhead). Default is 100.

Details

calculate the great circle distance between 2 points with Haversine formula, which deliberately ignores elevation differences.

Haversine formula (from R.W. Sinnott, "Virtues of the Haversine", Sky and Telescope, vol. 68, no. 2, 1984, p. 159):

dlon = lon2 - lon1

dlat = lat2 - lat1

a = sin^2(dlat/2) + cos(lat1) * cos(lat2) * sin^2(dlon/2)

c = 2 * arcsin(min(1,sqrt(a)))

d = R * c

dist_wlatlng_mi_cpp:

calculate distance between coordinate1<lat1, lng1> and coordinate2<lat2, lng2> in mile

dist_wlatlng_km_cpp:

calculate distance between coordinate1<lat1, lng1> and coordinate2<lat2, lng2> in kilometer

distSgl_wlatlng_cpp:

calculate distance between coordinate1<lat1, lng1> and coordinate2<lat2, lng2> in mile (measure = "mi") or kilometer (measure = "km"), default is mile.

implement as serial computing over vector of lat1, lng1, lat2, lng2

distRpl_wlatlng_cpp:

calculate distance between coordinate1<lat1, lng1> and coordinate2<lat2, lng2> in mile (measure = "mi") or kilometer (measure = "km"), default is mile.

implement as parallel computing over vector of lat1, lng1, lat2, lng2 via RcppParallel

gyang274/skm documentation built on May 17, 2019, 9:41 a.m.