r - 计算两个以上数据点之间的方位

Question

我有一些跟踪数据，我想计算 bearing在轨道的过程中。对于两点，我们可以使用 fossil 中的函数包裹:

# earth.bear(long1, lat1, long2, lat2)
earth.bear(-10.54427, 52.11112, -10.55493, 52.10944)
# 255.6118

但是，这不会超过两点。以下是一些示例数据:

tracks <- read.table(text = 
"latitude,  longitude
52.111122,  -10.544271
52.10944,   -10.554933
52.108898,  -10.558025
52.108871,  -10.560946
52.113991,  -10.582005
52.157223,  -10.626506
52.194977,  -10.652878
52.240215,  -10.678817
52.26421,   -10.720366
52.264015,  -10.720642", header = TRUE, sep = ",")

Answer 1

尝试这个:

sum(
  sapply(1:(nrow(tracks) - 1), function(i){
    earth.bear(tracks$longitude[i], tracks$latitude[i],
               tracks$longitude[i+1], tracks$latitude[i+1] )

  })
)

# 2609.871