使用ggplot绘制地图并在地图上绘制点

Question

我在苏格兰酿酒厂的数据集上工作，我想在地图上可视化它们的位置。所以我用下面的代码像这样绘制了苏格兰及其周边地区：

library(SpatialEpi)
library(tmap)
library("sf")
library("rnaturalearth")
library("rnaturalearthdata")
library("rgeos")
library("ggspatial")
library("ggrepel")

world <- ne_countries(scale = "medium", returnclass = "sf")
ggplot(data = world) +
  geom_sf() +
  coord_sf(xlim = c(-13.68, 0.72), ylim = c(54.63, 60.85), expand = FALSE)

之后，我使用数据集威士忌的Longitude/Latitude-information，并尝试将酒厂绘制为点（数据集可在此处下载：whisky）：

whisky <- read.csv("whisky_data.csv")
mapdata <- whisky[,c(1,15:16)]
mapdata$Latitude <- as.numeric(mapdata$Latitude)
mapdata$Longitude <- as.numeric(mapdata$Longitude)

coordinates(mapdata)<-~Longitude+Latitude
class(mapdata)

# does it have a projection/coordinate system assigned?
proj4string(mapdata)  # Nope

# check coordinate system of world
st_crs(world)  # +proj=longlat +datum=WGS84

# manually tell R what the coordinate system is
proj4string(mapdata)<-CRS("+proj=longlat +datum=WGS84")

ggplot(data = world) +
  geom_sf() +
  coord_sf(xlim = c(-13.68, 0.72), ylim = c(54.63, 60.85), expand = FALSE) +
  geom_point(data=as.data.frame(mapdata), aes(x=Longitude, y=Latitude), color="red")

但是地图上没有显示任何点。我想我没有正确转换坐标以绘制到世界地图中？

由于我是制图方面的绝对初学者，我非常感谢您对此提供的任何帮助！！非常感谢！ :)

Answer 1

你的箱子很结实/威士忌，多么可爱的词？

考虑这段代码；它建立在 {sf} 包和 ggplot2::geom_sf() 函数之上。有关详细信息，请查看 RStudio 论坛上的 post，讨论绘制地图的其他选项 https://community.rstudio.com/t/best-packages-for-making-map-leaflet-vs-ggmap-vs-sf-vs/38403/2?u=jlacko

但无论如何，这段代码应该可以帮助您入门。

library(sf) # general spatial manipulation
library(giscoR) # for the shape of Scotland
library(dplyr) # general data frame manipulation
library(ggplot2) # because ggplot...

# Scotland as a spatial object
scotland <- giscoR::gisco_get_nuts(nuts_id = 'UKM',
                                   resolution = '01') 

# yer data
distilleries <- read.csv("whisky_data.csv") %>% 
  st_as_sf(coords = c("Latitude", "Longitude"), crs = 4326)

# a quick reality check - looks legit
mapview::mapView(distilleries)

# a ggplot object
ggplot() +
  geom_sf(data = scotland, fill = NA, color = "gray45") + # borders of Scotland
  geom_sf(data = distilleries, pch = 4, color = "red") + # the distilleries
  theme_void() +
  labs(title = "Distilleries of Scotland") +
  theme(plot.title = element_text(hjust = 1/2))

使用ggplot绘制地图并在地图上绘制点

Drawing map with ggplot and draw dots in map

r

coordinates

sf