英文:
simple feature - create new points with certain properties
问题
我有一个simple features，其中包含一个简单的点，我想在该点周围创建6个均匀分布且距离原始点100米的新点。在R（sf）中是否容易解决这个问题，你是否有可能提供一个类似这样的实现示例？
英文:
I've a simple features with a simple point, arround this point I like to create 6 new points equal distributed and 100 meter away from the orginal point. Is this easily solvable in R (sf) and do you have perhaps an example how I could implement something like this?
答案1
得分: 1
开始时将点缓冲100米，将其转换为线串，然后对缓冲的线串进行采样：
library(sf)#> 链接到 GEOS 3.8.0、GDAL 3.0.4、PROJ 6.3.1；sf_use_s2() 为 TRUElibrary(tidyverse)set.seed(41)point <- st_sfc(st_point(c(0, 51.5))) %>% st_set_crs(4326) # 伦敦附近的一个点buffer <- st_buffer(point, dist = 100) %>%st_cast('LINESTRING')six_points <- st_sample(buffer, size = 6, type = 'regular')#> 尽管坐标是经度/纬度，st_sample 假设它们是平面的#距离：six_points %>% st_as_sf() %>% st_cast('POINT') %>% st_distance(point)#> 单位：[m]#> [,1]#> [1,] 100.5366#> [2,] 100.2739#> [3,] 100.7187#> [4,] 100.5599#> [5,] 100.2410#> [6,] 100.6761
差不多了。如果需要厘米级精度，选择更好的坐标系会有帮助。
ggplot() +geom_sf(data = point, col = 'red') +geom_sf(data = buffer) +geom_sf(data = six_points, color = 'turquoise', size = 4) +theme_void()
在地图上：
library(mapview)mapview(point) +buffer +six_points
<sup>由 reprex 包 (v2.0.1) 于 2023-03-31 创建</sup>
英文:
Start by buffering the point by 100 meters, cast it to a linestring, and then sample the buffered linestring:
library(sf)#> Linking to GEOS 3.8.0, GDAL 3.0.4, PROJ 6.3.1; sf_use_s2() is TRUElibrary(tidyverse)set.seed(41)point <- st_sfc(st_point(c(0, 51.5))) %>% st_set_crs(4326) # a point around Londonbuffer <- st_buffer(point, dist = 100) %>%st_cast('LINESTRING')six_points <- st_sample(buffer, size = 6, type = 'regular')#> although coordinates are longitude/latitude, st_sample assumes that they are#> planar#distances:six_points %>% st_as_sf() %>% st_cast('POINT') %>% st_distance(point)#> Units: [m]#> [,1]#> [1,] 100.5366#> [2,] 100.2739#> [3,] 100.7187#> [4,] 100.5599#> [5,] 100.2410#> [6,] 100.6761
Pretty close. Choosing a better crs would help if you need cm accuracy.
ggplot() +geom_sf(data = point, col = 'red') +geom_sf(data = buffer) +geom_sf(data = six_points, color = 'turquoise', size = 4) +theme_void()
On a map:
library(mapview)mapview(point) +buffer +six_points
<sup>Created on 2023-03-31 by the reprex package (v2.0.1)</sup>
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