r的距离距离点的距离点

Question

I有一个空间矢量（spatoods），分组以分组为单位。我想计算每个点到组中的第一个点的距离。

    Trans2024_df
    Name  Distance_to_first
1   T01   0
2   T01   1.2
3   T01   2.5
4   T02   0
5   T02   0.5
6   T02   1.2
7   T02   1.7
8   T03   0
9   T03   1.3

我设法达到了前面的距离。

VectorPoints_sf <- st_as_sf(VectorPoints)

VectorPoints_sf %>%
  mutate(
    distance_next = sf::st_distance(
      geometry, 
      lead(geometry), 
      by_element = TRUE))

    Name  distance_next
1   T01   0
2   T01   1.2
3   T01   1.3
4   T02   5
5   T02   0.5
6   T02   0.7
7   T02   1.5
8   T03   2
9   T03   1.3

但我不知道如何到达第一个点的距离。
我以为它可以与dplr :: first（）

一起使用

VectorPoints_sf %>%
  group_by(Transect) %>%
  mutate(
    distance_first = sf::st_distance(
      geometry, 
      first(geometry), 
      by_element = TRUE))

但是我会收到以下错误：

    Error in `stopifnot()`:
ℹ In argument: `distance_first = sf::st_distance(geometry, geometry[1], by_element = TRUE)`.
ℹ In group 1: `Transect = "T09"`.
Caused by error in `sf::st_distance()`:
! length(x) == length(y) is not TRUE

Answer 1

library(terra)
v <- vect(matrix(runif(40), ncol=2), crs="local")
v$ID <- sample(rep(LETTERS[1:5], each=4))

缩小距离

x <- lapply(split(v, "ID"), \(x) distance(x[1], x[-1]))

将它们一起在data.frame

中输入

do.call(rbind, lapply(names(x), \(i) data.frame(group=i, dist=t(x[[i]]))))
#   group      dist
#1      A 0.8582356
#2      A 0.9665782
#3      A 0.6253639
#4      B 0.3387519
#5      B 0.6647694
#6      B 0.3004775
#7      C 0.5647327
#8      C 0.8115395
#9      C 0.4722487
#10     D 0.7140878
#11     D 0.8428825
#12     D 0.5384567
#13     E 0.8268007
#14     E 0.6973941
#15     E 0.5094854