我的代码可以很好地生成从 A 点到 B 点的地图和线条,但是对于远东半球的国家,该线尝试穿过最短路径(例如从澳大利亚向东)并中断以创建一条穿过地块的直线。有什么建议么?我缩短了代码并将其全部包含在下面以供使用。
有人提到(在代码的链接中)使用伟大的圆圈,但我无法让它工作。
Thanks!
adds <- c("Argentina",
"Australia",
"Germany",
"Japan",
"Korea")
# people are coming 'from' all those spots 'to' heidelberg
add0 <- "Salt Lake City, UT"
# get lat / lon
from <- geocode(adds)
to <- geocode(add0)
from
# see: http://flowingdata.com/2011/05/11/how-to-map-connections-with-great-circles/
library(maps)
library(geosphere)
# will need to adjust these limits...
xlim <- c(-170, 200)
ylim <- c(-50, 95)
quartz(file = "UCC.pdf",
type = "pdf",
height = 5, width = 9)
#print the map itself
map("world",
fill=TRUE,
xlim=xlim,
ylim=ylim,
# projection = "mercator",
# orientation=c(90,-111, 0),
col = grey(0.50),
bg = grey(0.08),
lwd=0.05)
# following gets the 2D projection of a line moving between two points on a sphere
for (i in 1:nrow(from)) {
inter <- gcIntermediate(c(from[i, "lon"],
from[i, "lat"]),
c(to[1, "lon"],
to[1, "lat"]),
n=500, addStartEnd = T)
# and plot lines
lines(inter,
col = grey(0.90),
lwd = 1)
}
dev.off()