在 R 中的 highchart 地图上绘制任意线（图书馆 highcharter）

Question

我正在使用 R 中的 highcharter 包绘制一个 highcharts 地图。我已经添加了一些点（城市），并希望通过使用世界地图坐标绘制一条附加直线来链接它们。

我已经设法绘制直线，首先绘制地图，然后将鼠标悬停在显示绘图坐标的城市上，然后使用上述绘图坐标重新绘制绘图。 （注意：我使用了 PLOT 坐标，而我的目标是直接使用 WORLD MAP 坐标。） 如果你只有一两个城市，那没什么大不了的。但是如果你有 100 个城市/点，那就很烦人了。我想答案会是这样的：Is it possible to include maplines in highcharter maps?。

谢谢！

这是我的代码：

library(highcharter)
library(tidyverse)    

# cities with world coordinates
ca_cities <- data.frame(
  name = c("San Diego", "Los Angeles", "San Francisco"),
  lat = c(32.715736, 34.052235, 37.773972), # world-map-coordinates
  lon = c(-117.161087, -118.243683, -122.431297) # world-map-coordinates
)

# path which I create AFTER the first drawing of the map as I get the 
# plot-coordinates when I hover over the cities.
path <- "M669.63,-4963.70,4577.18,-709.5,5664.42,791.88"
# The goal: the path variable above should be defined using the WORLD-
# coordinates in ca_cities and not using the PLOT-coordinates.

# information for drawing the beeline
ca_lines <- data.frame(
  name = "line",
  path = path, 
  lineWidth = 2
)

# construct the map
map <- hcmap("countries/us/us-ca-all", showInLegend = FALSE) %>%
  hc_add_series(data = ca_cities, type = "mappoint", name = "Cities") %>%
  hc_add_series(data = ca_lines, type = "mapline", name = "Beeline", color = "blue") 
map

See picture here

Answer 1

几个小时后，我找到了问题的答案。也许有更简单的方法，但我将使用 rgdal-package 发布我的版本。 我们的想法是首先将世界地图坐标转换为特定地图的坐标系 (ESRI)，然后从 highcharts 反向转换所有调整：

library(highcharter)
library(tidyverse)    
library(rgdal) # you also need rgdal

# cities with world coordinates
ca_cities <- data.frame(
  name = c("San Diego", "Los Angeles", "San Francisco"),
  lat = c(32.715736, 34.052235, 37.773972), 
  lon = c(-117.161087, -118.243683, -122.431297) 
)

# pre-construct the map
map <- hcmap("countries/us/us-ca-all", showInLegend = FALSE) 

# extract the transformation-info
trafo <- map$x$hc_opts$series[[1]]$mapData$`hc-transform`$default

# convert to coordinates
ca_cities2 <- ca_cities %>% select("lat", "lon")
coordinates(ca_cities2) <- c("lon", "lat")

# convert world geosystem WGS 84 into transformed crs
proj4string(ca_cities2) <- CRS("+init=epsg:4326") # WGS 84
ca_cities3 <- spTransform(ca_cities2, CRS(trafo$crs)) # 

# re-transform coordinates according to the additionnal highcharts-parameters
image_coords_x <- (ca_cities3$lon - trafo$xoffset) * trafo$scale * trafo$jsonres + trafo$jsonmarginX
image_coords_y <- -((ca_cities3$lat - trafo$yoffset) * trafo$scale * trafo$jsonres + trafo$jsonmarginY)

# construct the path
path <- paste("M",
              paste0(paste(image_coords_x, ",", sep = ""), 
              image_coords_y, collapse = ","), 
              sep = "")

# information for drawing the beeline
ca_lines <- data.frame(
  name = "line",
  path = path, 
  lineWidth = 2
)

# add series
map <- map %>%
  hc_add_series(data = ca_cities, type = "mappoint", name = "Cities") %>%
  hc_add_series(data = ca_lines, type = "mapline", name = "Beeline", color = "blue") 

map