## ---- echo=FALSE, include=FALSE-----------------------------------------------
library(knitr)
library(geosphere)
opts_chunk$set(
	fig.width = 5,	fig.height = 5,	fig.cap = '',collapse = TRUE
)


## ---- geo5a-------------------------------------------------------------------
library(geosphere)
LA <- c(-118.40, 33.95)
NY <- c(-73.78,  40.63)

destPoint(LA, b=65, d=100000)
circle=destPoint(c(0,80), b=1:365, d=1000000)
circle2=destPoint(c(0,80), b=1:365, d=500000)
circle3=destPoint(c(0,80), b=1:365, d=100000)
plot(circle, type='l')
polygon(circle, col='blue', border='black', lwd=4)
polygon(circle2, col='red', lwd=4, border='orange')
polygon(circle3, col='white', lwd=4, border='black')


## ---- geo10-------------------------------------------------------------------
MS <- c(-93.26, 44.98)
gc1 <- greatCircleBearing(NY, 281)
gc2 <- greatCircleBearing(MS, 195)
gc3 <- greatCircleBearing(LA, 55)
data(wrld)
plot(wrld, type='l', xlim=c(-125, -70), ylim=c(20, 60))
lines(gc1, col='green')
lines(gc2, col='blue')
lines(gc3, col='red')

int <- gcIntersectBearing(rbind(NY, NY, MS), 
            c(281, 281, 195), rbind(MS, LA, LA), c(195, 55, 55))
int
distm(rbind(int[,1:2], int[,3:4]))
int <- int[,1:2]
points(int)
poly <- rbind(int, int[1,])
centr <- centroid(poly)
poly2 <- makePoly(int)
polygon(poly2, col='yellow')
points(centr, pch='*', col='dark red', cex=2)


## ---- geo5b-------------------------------------------------------------------
d <- distCosine(LA, NY)
d
b <- bearing(LA, NY)
b
destPoint(LA, b, d)
NY
finalBearing(LA, NY)


## ---- geo12-------------------------------------------------------------------
atd <- alongTrackDistance(LA, NY, MS)
p <- destPoint(LA, b, atd)
plot(wrld, type='l', xlim=c(-130,-60), ylim=c(22,52))
gci <- gcIntermediate(LA, NY)
lines(gci, col='blue', lwd=2)
points(rbind(LA, NY), col='red', pch=20, cex=2)
points(MS[1], MS[2], pch=20, col='blue', cex=2)
lines(gcIntermediate(LA, p), col='green', lwd=3)
lines(gcIntermediate(MS, p), col='dark green', lwd=3)
points(p, pch=20, col='red', cex=2)
dist2gc(LA, NY, MS)
distCosine(p, MS)


## ---- , geo16, fig.width=9----------------------------------------------------
NP <- c(0, 85)
SF <- c(-122.44, 37.74)
bearing(SF, NP)
b <- bearingRhumb(SF, NP)
b
dc <- distCosine(SF, NP)
dr <- distRhumb(SF, NP)
dc / dr

pr <- destPointRhumb(SF, b, d=round(dr/100) * 1:100)
pc <- rbind(SF, gcIntermediate(SF, NP), NP)
par(mfrow=c(1,2))
plot(wrld, type='l', xlim=c(-140,10), ylim=c(15,90), main='Equirectangular')
lines(pr, col='blue')
lines(pc, col='red')
data(merc)
plot(merc, type='l', xlim=c(-15584729, 1113195), 
                     ylim=c(2500000, 22500000), main='Mercator')
lines(mercator(pr), col='blue')
lines(mercator(pc), col='red')