寻找一种功能，该功能允许选择/识别与源面共享线段的面

问题描述

为了选择/识别shapefile的边界多边形，我想使用一个能够选择/识别与源多边形共享线段的多边形的函数.

In order to select/identify the border polygons of a shapefile, I would like to use a function able to select/identify polygon that share a line segment with a source polygon.

有数字:

我有这种shapefile:

I have this kind of shapefile:

使用rgeos包中的gUnionCascaded，我还有一个带有轮廓多边形"的shapefile.

Using gUnionCascaded from rgeos package, I have a second shapefile with the "contour polygon"

现在我正在寻找一个可以选择/识别边界多边形(在图上阴影)的函数，即与第二个shapefile的多边形共享线段的第一个shapefile的多边形. :

Now I am looking for a function that can select/identify border polygons (shaded on the fig) i.e. polygons of the first shapefile that share a line segment with the polygon of the second shapefile . :

推荐答案

正如Josh O'Brien所建议的那样，我使用了rgeos::gRelate()函数.我收到3个DE-9IM案件:

As proposed by Josh O'Brien, I have used the rgeos::gRelate() function.I get 3 DE-9IM cases:

x <- gRelate(shapefile.1, shapefile.2, byid = TRUE)
table(x)
2FF10F212 2FF11F212 2FF1FF212 
       63      2470    174495        

产生的DE-9IM字符串代码可以解释如下:

The resulted DE-9IM string codes can be interpreted as follow:

1)2FF1FF212:表示第一个shapefile中的多边形与第二个shapefile中的多边形的边界不相交

1) 2FF1FF212: represent polygons from the first shapefile that don't intersect the border of the polygon of the second shapefile

2)2FF11F212:表示第一个shapefile中的多边形，该多边形与第二个shapefile中的多边形的边界相交，

2) 2FF11F212: represent polygons from the first shapefile that intersect the border of the polygon of the second shapefile with a line

3)2FF10F212:表示第一个shapefile中的多边形，该多边形与第二个shapefile中的多边形的边界与点相交

3) 2FF10F212: represent polygons from the first shapefile that intersect the border of the polygon of the second shapefile with a point

最后两种情况是我要寻找的边界多边形.我有他们的ID:

The two last cases are my border polygons that I was looking for.I have got their ID with:

poly.border <- which(x %in% c("2FF10F212","2FF11F212"))

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