在R中使用deckgl进行空间数据可视化

我想提供一个示例，说明如何使用R中的deckgl软件包绘制3D地图图。我从Mapbox在地图布局上生成条形图。

首先，我定义了在datascienceplus.com上找到的“开放街道地图”地理编码功能。它使用Open Street Map API（OSM-API）将地址字符串地理编码为经度和纬度坐标。

## 文件资料: http://wiki.openstreetmap.org/wiki/Nominatim
# 资源: https://datascienceplus.com/osm-nominatim-with-r-getting-locations-geo-coordinates-by-its-address/
osm_geocoder <- function(address = NULL)
{
  if(suppressWarnings(is.null(address)))
    return(data.frame())
  
  tryCatch(
    d <- jsonlite::fromJSON( 
      gsub('\\@addr\\@', gsub('\\s+', '\\%20', address), 
           'http://nominatim.openstreetmap.org/search/@addr@?format=json&addressdetails=0&limit=1')
    ), error = function(c) return(data.frame())
  )
  
  if(length(d) == 0) 
    return(data.frame())
  
  return(data.frame(lon = as.numeric(d$lon), lat = as.numeric(d$lat)))
}

之后，我用城市名称建立一个列表。我将此列表提供给地理编码功能，从而生成一个地理编码的数据帧。

city_list <- c("Frankfurt, Germany",
               "Dortmund, Germany",
               "Berlin, Germany",
               "Stuttgart, Germany",
               "Karlsruhe, Germany",
               "Zurich, Switzerland", 
               "Wien, Austria", 
               "Bern, Switzerland",
               "Munich, Germany",
               "Marburg, Germany",
               "Giessen, Germany",
               "Pforzheim, Germany",
               "Cologne, Germany", 
               "Essen, Germany", 
               "Heidelberg, Germany",
               "Kassel, Germany",
               "Paderborn, Germany",
               "Leipzig, Germany",
               "Dresden, Germany",
               "Nuremberg, Germany",
               "Augsburg, Germany",
               "Regensburg, Germany",
               "Pilsen, Czech Republic",
               "Linz, Austria",
               "Innsbruck, Austria",
               "Bamberg, Germany",
               "Fulda, Germany",
               "Hanover, Germany",
               "Wolfsburg, Germany",
               "Magdeburg, Germany",
               "Jena, Germany",
               "Chemnitz, Germany",
               "Zwickau, Germany",
               "Cottbus, Germany",
               "Bautzen, Germany",
               "Mainz, Germany",
               "Bonn, Germany",
               "Duesseldorf, Germany",
               "Trier, Germany",
               "Mannheim, Germany",
               "Aachen, Germany",
               "Freiburg, Germany",
               "Ulm, Germany",
               "Kempten, Germany",
               "Ingolstadt, Germany")

# 让我们生成一个可用于add_grid_layer函数的数据框
data_df_columns <- data.frame(matrix(nrow=3500*length(city_list),ncol=4))
colnames(data_df_columns) <- c("ADDRESS","RACKS","SPACES","COORDINATES")

data_df_columns$RACKS <- 2
data_df_columns$SPACES <- 4

for(i in 1:length(city_list)){
  print(i)
  dum_coord <- osm_geocoder(city_list[i])
  for(j in 1:3500){
    data_df_columns$ADDRESS <- paste0(city_list[i]," : ",j)
    dum_long <- rnorm(1, mean=as.numeric(dum_coord[1]),sd=0.75)  
    dum_lat <- rnorm(1,mean=as.numeric(dum_coord[2]),sd=0.75)
    data_df_columns$COORDINATES[(i-1)*3500+j] <- list(c(dum_long, dum_lat))
  }
}

properties_grid <- list(
  pickable = TRUE,
  extruded = TRUE,
  cellSize = 1600,
  elevationScale = 8,
  coverage = 0.5,
  colorRange = list(c(0,255,255),
                    c(0,204,255),
                    c(0,153,255),
                    c(0,51,255),
                    c(0,0,255),
                    c(0,0,204)),
  getPosition = JS("data => data.COORDINATES"),
  getTooltip = JS("object => object.count")
)

一旦有了包含用地理编码功能进行地理编码的人为创建的空间数据点的数据集，就可以使用R中的deckgl包对其进行绘制。底图是在Mapbox中创建的。

deckgl(zoom = 10, pitch = 120, longitude = 8.682092, latitude = 50.11064) %>%
  add_grid_layer(data = data_df_columns,properties = properties_grid) %>%
  add_mapbox_basemap(style = "mapbox://styles/linnartsf/cjq6p9q8f8zwf2rp74qf2o3d5")