ggmap/sf 是否仍然在错误的位置绘制点？

Question

这个老错误仍然尚未解决，还是有合理的解决方法？

部分城市：

require(ggplot2)
require(ggmap)
require(sf)

cities = sf::read_sf('{
  "type": "FeatureCollection",
  "name": "cities",
  "crs": {
    "type": "name",
    "properties": {
      "name": "urn:ogc:def:crs:OGC:1.3:CRS84"
    }
  },
  "features": [{
      "type": "Feature",
      "properties": {
        "city": "London"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [-0.13, 51.51]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "city": "Rome"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [12.48, 41.89]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "city": "Stockholm"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [18.07, 59.33]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "city": "Istanbul"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [28.96, 41.01]
      }
    }
  ]
}
')

还有 ggmap 底图：

bb = c(left = -11, bottom = 35, right = 42, top = 65)
europe = ggmap::get_stamenmap(bbox = bb, maptype = 'toner-lite', zoom = 3)

ggmap(europe) + 
  geom_sf(data = cities, inherit.aes = FALSE, col = 'red', size = 3)

Answer 1

我认为问题在于

ggmap

使用坐标对象

CoordMap

来决定栅格像素的放置位置。通过切换到

coord_sf

（当您添加

geom_sf

图层时会发生这种情况），您将导致栅格不对齐。如果您提取点的坐标，您可以简单地将它们叠加为

geom_point

层：

ggmap(europe) + 
  geom_point(data = as.data.frame(st_coordinates(cities)), aes(X, Y), 
             inherit.aes = FALSE, col = 'red', size = 3)