导出KML文件以在Google Maps中使用。以下是导出的代码(改编自这里):
t_expkml_c <- function(obj, archivo,
col_nombre, col_desc, col_color,
mapa_colores = "mapa_colores_topaz",
mapa_nombre = "Mapa_TSE", mapa_desc = "Mapa Creado por PE de TSE") {
# - changes projection
if (proj4string(obj)!="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +towgs84=0,0,0") {
cat("Input SpatialPolygonsDataFrame ",obj," re-projected from ",
proj4string(obj)," to WGS84 longlat\n",sep="")
assign(obj,spTransform(obj,CRS(" +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +towgs84=0,0,0")))
} # check projection
# opens file
kmlFile <- file(archivo,
open = "w")
# goes through each polygon
# usa maptools::kmlPolygon
Xout <- sapply(slot(obj,
"polygons"),
function(x) {
maptools::kmlPolygon(x, # Object
name = as(obj, "data.frame")[slot(x, "ID"), col_nombre],
# name column
col = mapa_colores[as.numeric(as(obj, "data.frame")[slot(x, "ID"), col_color])],
# color column
lwd = 0.5, # stroke
border = NA, # borders
visibility = TRUE,
description = as(obj,"data.frame")[slot(x, "ID"), col_desc], #description (what I need to change)
)
}
)
# export polyon out
cat(kmlPolygon(kmlname=mapa_nombre,
kmldescription=mapa_desc)$header,
file = kmlFile, sep="\n")
# estilos
cat(unlist(Xout["style",]),
file = kmlFile, sep="\n")
# contenidos
cat(unlist(Xout["content",]),
file = kmlFile, sep="\n")
# footers
cat(kmlPolygon()$footer,
file = kmlFile, sep="\n")
close(kmlFile) # end
}
当我只从kmlmap@data
数据框中选择一列时(该对象是SpatialPolygonsDataFrame
类),这个方法运行得很好。然而,我想要导出一个更大的数据表格,以便它可以显示在Google Maps形状的描述中。
如果我想添加其他描述符,我会像这样在Google Maps中更改数据表:
但我想要在R中复制原始导出的这种行为。我尝试更改description
参数以添加列名称的向量或甚至是列名称的索引(即c("Column2", "Column3")
或1:2
),并尝试将HTML添加到描述列(当在Google Maps数据表中不同的列中可视化时,这显然不起作用)。
我该如何实现这个目标?
add_kml()
函数,它将允许您从R内部绘制KML地图) - SymbolixAU