向SpatialPolygonsDataFrame添加多边形 [英] Adding a Polygon to a SpatialPolygonsDataFrame

问题描述

如何在SpatialPolygonsDataFrame中添加多边形?

How to add an polygon to a SpatialPolygonsDataFrame?

示例:下面的脚本将创建一个SpatialPolygonsDataFrame.我想添加一个多边形，该多边形由围绕现有多边形的大正方形组成.

Example: The script underneath will create a SpatialPolygonsDataFrame. I would like to add a polygon which consists of a large square around the existing polygons.

   library(rgdal)
   dsn <- system.file("vectors", package = "rgdal")[1]
   Scotland <- readOGR(dsn=dsn , layer="scot_BNG")
   plot(Scotland)

首选最终结果:

重要的是，矩形必须成为SpatialPolygonsDataFrame的一部分.由于我必须对数据框进行一些计算.因此，手动添加正方形的可视层是不够的.

It is important that the rectangle becomes part of the SpatialPolygonsDataFrame. Since I have to do some calculation of the dataframe. So manually adding a visual layer of a square is insufficient.

谢谢！

推荐答案

下面的代码创建一个包围原始空间多边形的矩形，并将其作为空间多边形添加到原始形状.

The following code creates a rectangle that encloses the original spatial polygons and adds this as a spatial polygon to the original shape.

library(rgdal)
library(rgeos)

dsn <- system.file("vectors", package = "rgdal")[1]
Scotland <- readOGR(dsn=dsn , layer="scot_BNG")

# change the width parameter to make the rectangle the desired size
# this results in an extent object that surrounds the original shape
eScotland <- extent(gBuffer(Scotland, width = 50000))
# turn the extent into a Spatial Polygon
pScotland <- as(eScotland, 'SpatialPolygons')
crs(pScotland) <- crs(Scotland)
newScotland <- bind(pScotland, Scotland)
plot(newScotland)

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