projectPoints: Project lat-lon points

Description

Project long lat points to e.g. UTM projection. Basics copied from OpenStreetMap::projectMercator

Usage

projectPoints(
  lat,
  long,
  data,
  from = pll(),
  to = putm(long = long),
  dfout = TRUE,
  drop = FALSE,
  quiet = FALSE
)

Value

data.frame (or matrix, if dfout=FALSE) with points in new projection

Arguments

lat, long: Latitude (North/South) and longitude (East/West) coordinates in decimal degrees
data: Optional: data.frame with the columns lat and long
from: Original Projection CRS (do not change for latlong-coordinates). DEFAULT: pll() = sf::st_crs("+proj=longlat +datum=WGS84")
to: target projection CRS (Coordinate Reference System) Object. Other projections can be specified as sf::st_crs("your_proj4_character_string"). DEFAULT: putm(long=long)
dfout: Convert output to data.frame to allow easier indexing? DEFAULT: TRUE
drop: Drop to lowest dimension? DEFAULT: FALSE (unlike projectMercator)
quiet: Suppress warning about NA coordinates and non-df warning in getColumn? DEFAULT: FALSE

Author

Berry Boessenkool, berry-b@gmx.de, Jun 2016

Examples

Run this code

library("OpenStreetMap")
lat <- runif(100, 6, 12)
lon <- runif(100, 48, 58)
plot(lat,lon, main="flat earth unprojected")
plot(projectMercator(lat,lon), main="Mercator")
plot(projectPoints(lat,lon), main="UTM32")
stopifnot(all( projectPoints(lat,lon, to=posm()) == projectMercator(lat,lon) ))

projectPoints(c(52.4,NA),      c(13.6,12.9))
projectPoints(c(52.4,NA),      c(13.6,12.9), quiet=TRUE)
projectPoints(c(52.4,52.3,NA), c(13.6,12.9,13.1))
projectPoints(c(52.4,52.3,NA), c(13.6,NA  ,13.1))
projectPoints(c(52.4,52.3,NA), c(NA  ,12.9,13.1))

# Reference system ETRS89 with GRS80-Ellipsoid (common in Germany)
set.seed(42)
d <- data.frame(N=runif(50,5734000,6115000), E=runif(50, 33189000,33458000))
d$VALUES <- berryFunctions::rescale(d$N, 20,40) + rnorm(50, sd=5)
head(d)
c1 <- projectPoints(lat=d$N, long=d$E-33e6, to=pll(),
          from=sf::st_crs("+proj=utm +zone=33 +ellps=GRS80 +units=m +no_defs") )
c2 <- projectPoints(y, x, data=c1, to=posm() )
head(c1)
head(c2)

if (FALSE)  # not checked on CRAN because of file opening
map <- pointsMap(y,x, c1, plot=FALSE)
pdf("ETRS89.pdf")
par(mar=c(0,0,0,0))
plot(map)
rect(par("usr")[1], par("usr")[3], par("usr")[2], par("usr")[4],
     col=berryFunctions::addAlpha("white", 0.7))
scaleBar(map, y=0.2, abslen=100)
points(c2)
berryFunctions::colPoints(c2$x, c2$y, d$VALUE )
dev.off()
berryFunctions::openFile("ETRS89.pdf")
#unlink("ETRS89.pdf")