r语言 - 如何将坐标列表转换为SF Multipolygon文件?

Question

newdata
V1        V2
1    -2.8701091 8273.6321
2     4.8298909 8273.6321
3    21.3298909 8279.1321
4    25.7298909 8281.3321
5    32.3298909 8285.7321
6    46.6298909 8298.9321

V1是x, V2是y，我想知道是否有一种方法将其转换为sf多多边形文件。Newdata有941个多边形，每个多边形大约有19行。谢谢你！以下是前两个多边形的可复制数据集:

> dput(head(newdata, 38))
structure(list(.id = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), V1 = c(-2.8701090548579, 
4.8298909451421, 21.3298909451421, 25.7298909451421, 32.3298909451421, 
46.6298909451421, 47.7298909451421, 55.4298909451421, 64.2298909451421, 
67.5298909451421, 67.5298909451421, 65.3298909451421, 54.3298909451421, 
52.1298909451421, 48.8298909451421, 46.6298909451421, 34.5298909451421, 
-2.8701090548579, -2.8701090548579, -1.79600509987251, 9.2039949001275, 
20.2039949001275, 25.7039949001275, 37.8039949001275, 41.1039949001275, 
44.4039949001275, 44.4039949001275, 38.9039949001275, 35.6039949001275, 
33.4039949001275, 32.3039949001275, 29.0039949001275, 20.2039949001275, 
16.9039949001275, 11.4039949001275, 0.403994900127497, -1.79600509987251, 
-1.79600509987251), V2 = c(8273.63213813615, 8273.63213813615, 
8279.13213813615, 8281.33213813615, 8285.73213813615, 8298.93213813615, 
8300.03213813615, 8313.23213813615, 8333.03213813615, 8356.13213813615, 
8381.43213813615, 8385.83213813615, 8401.23213813615, 8403.43213813615, 
8405.63213813615, 8406.73213813615, 8406.73213813615, 8395.73213813615, 
8273.63213813615, 7198.72511687208, 7198.72511687208, 7199.82511687208, 
7202.02511687208, 7213.02511687208, 7216.32511687208, 7222.92511687208, 
7236.12511687208, 7251.52511687208, 7258.12511687208, 7261.42511687208, 
7262.52511687208, 7264.72511687208, 7269.12511687208, 7270.22511687208, 
7271.32511687208, 7271.32511687208, 7270.22511687208, 7198.72511687208
)), row.names = c(NA, 38L), class = "data.frame")

Answer 1

将R对象转换为{sf}对象正是{sfheaders}

的用例如果您的.id列指定了单个MULTIPOLYGON中的每个POLYGON，则使用参数polygon_id = ".id"

library(sf)
library(sfheaders)
sfheaders::sf_multipolygon(
obj = newData
, polygon_id = ".id"
, x = "V1"
, y = "V2"
)
Simple feature collection with 1 feature and 1 field
Geometry type: MULTIPOLYGON
Dimension:     XY
Bounding box:  xmin: -2.870109 ymin: 7198.725 xmax: 67.52989 ymax: 8406.732
CRS:           NA
id                       geometry
1  1 MULTIPOLYGON (((-2.870109 8...

如果你的.id列代表每个MULTIPOLYGON，使用参数multipolygon_id = ".id"

sfheaders::sf_multipolygon(
obj = newData
, multipolygon_id = ".id"
, x = "V1"
, y = "V2"
)
Simple feature collection with 2 features and 1 field
Geometry type: MULTIPOLYGON
Dimension:     XY
Bounding box:  xmin: -2.870109 ymin: 7198.725 xmax: 67.52989 ymax: 8406.732
CRS:           NA
.id                       geometry
1   1 MULTIPOLYGON (((-2.870109 8...
2   2 MULTIPOLYGON (((-1.796005 7...