R sf:LinearRing 的点不形成闭合线串 [英] R sf: Points of LinearRing do not form a closed linestring

问题描述

我正在尝试计算一组多边形的质心.

I am trying to calculate the centroids of a set of polygons.

我的数据集geodata 包含五列，其中包括一列sfc_GEOMETRY 的geometry 列，有45759 行.

My dataset, geodata, contains five columns including one geometry column of class sfc_GEOMETRY, with 45759 rows.

当我运行 sf::st_centroid(geodata) 时，我收到以下消息

When I run sf::st_centroid(geodata), I get the following message

CPL_geos_op("centroid", x, numeric(0), integer(0), numeric(0), Error in CPL_geos_op("centroid", x, numeric(0), integer(0), numeric(0), : Evaluation error: IllegalArgumentException: Points of LinearRing do not form a closed linestring.

Error in CPL_geos_op("centroid", x, numeric(0), integer(0), numeric(0), : Evaluation error: IllegalArgumentException: Points of LinearRing do not form a closed linestring.

此外:警告消息:

1:在 st_centroid.sf(geodata) 中:st_centroid 假设属性在 x 的几何上是恒定的

1: In st_centroid.sf(geodata) : st_centroid assumes attributes are constant over geometries of x

2: 在 st_centroid.sfc(st_geometry(x), of_largest_polygon = of_largest_polygon) 中:st_centroid 没有为经度/纬度数据提供正确的质心

2: In st_centroid.sfc(st_geometry(x), of_largest_polygon = of_largest_polygon) : st_centroid does not give correct centroids for longitude/latitude data

• 我应该运行一个循环来检测哪个几何图形没有闭合吗?
• 这是我的几何类的问题吗?应该是sfc_MULTIPOLYGON吗?

我在通过循环读入文件列表时遇到了这个问题.循环会读入文件，然后将它们rbind 一起放入geodata，然后然后计算质心:

I was encountering this problem when reading in a list of files through a loop. The loop would read in the files and then rbind them together into geodata, and then calculate the centroid:

for(i in 1:length(list)){
  file <- st_read(list[i])
  geodata <- rbind(geodata, file) #geodata is here a void sf object
}
geocent <- st_centroid(geodata)

当我计算循环中的质心(对于列表中的每个文件)时，错误消失了.

When I calculated the centroids within the loop (for each file in the list), the error disappeared.

for(i in 1:length(list)){
  file <- st_read(list[i])
  file <- st_centroid(file)
  geocent <- rbind(geodata, file) #geodata is here a void sf object
}

因此，我认为问题在于绑定操作.

Hence, I think the problem lay in the binding operation.

• 也许我没有以正确的方式定义我的 void sf 对象.
• 也许 rbind 不是合适的函数，或者我应该指定它的参数.
• Perhaps I had not defined my void sf object in the right manner.
• Perhaps rbind was not the appropriate function, or I should have specified its parameters.

推荐答案

无需运行循环来查找哪个几何体不好.st_is_valid() 函数应该会告诉您哪些行有问题.

There's no need to run a loop to find which geometry is bad. The st_is_valid() function should tell you which row(s) have the problem.

您的几何图形之一可能由错误数量的点组成.

It looks like one of your geometries might be made up of an incorrect number of points.

有关在 r-spatial 中查找和解决问题的更多信息:https://www.r-spatial.org/r/2017/03/19/invalid.html

More info about finding and fixing the problem at r-spatial: https://www.r-spatial.org/r/2017/03/19/invalid.html

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