问题描述
> head(moves)
hiring start end
1 1 POINT (-2.030474 51.36306) POINT (-2.250102 51.41609)
2 2 POINT (-2.319776 51.46162) POINT (-2.491189 51.41029)
3 4 POINT (-2.025846 51.47712) POINT (-2.063781 51.49158)
4 6 POINT (-2.426711 51.38076) POINT (-2.132722 51.46999)
5 7 POINT (-2.116654 51.4887) POINT (-2.204403 51.51874)
6 8 POINT (-2.122917 51.5861) POINT (-2.134635 51.51806)
我需要逐行绘制从一个点到另一个点的线（理想情况下是尖的）。我的问题似乎是我的文件（移动）不是sf对象。我需要将其制成一种，还是将其中的数据转换成其他格式？
> dput(head(moves))
structure(list(hiring = c(1L,2L,4L,6L,7L,8L),start = list(
structure(c(-2.03047447566941,51.3630641761757),class = c("XY","POINT","sfg")),structure(c(-2.31977575385362,51.4616210429381
),structure(c(-2.02584648038463,51.4771163047678),structure(c(-2.42671091326068,51.3807643595824),structure(c(-2.1166538974769,51.4887039877758),structure(c(-2.12291705783767,51.5860957106472),"sfg"))),end = list(
structure(c(-2.25010169528537,51.4160891285008),structure(c(-2.49118920138511,51.4102939905029
),structure(c(-2.06378098244424,51.491583244303),structure(c(-2.13272163343155,51.469987047928),structure(c(-2.20440279315621,51.5187438721622),structure(c(-2.1346350057738,51.5180564842074),"sfg")))),row.names = c(NA,6L),class = "data.frame")
解决方法
带有基本图形的简单箭头，其背景为空（无图）。
编辑：使用原始帖子中给出的数据，我意识到moves$start和moves$end不是sfc对象，而只是sfg对象的列表。可以使用sfc将它们转换为sf::st_as_sfc对象，然后可以提取坐标。完整的代码是：
library(sf)
#> Linking to GEOS 3.8.0,GDAL 3.0.4,PROJ 6.3.1
moves <- structure(
list(hiring = c(1L,2L,4L,6L,7L,8L),start = list(
structure(c(-2.03047447566941,51.3630641761757),class = c("XY","POINT","sfg")),structure(c(-2.31977575385362,51.4616210429381),structure(c(-2.02584648038463,51.4771163047678),structure(c(-2.42671091326068,51.3807643595824),structure(c(-2.1166538974769,51.4887039877758),structure(c(-2.12291705783767,51.5860957106472),"sfg"))),end = list(
structure(c(-2.25010169528537,51.4160891285008),structure(c(-2.49118920138511,51.4102939905029),structure(c(-2.06378098244424,51.491583244303),structure(c(-2.13272163343155,51.469987047928),structure(c(-2.20440279315621,51.5187438721622),structure(c(-2.1346350057738,51.5180564842074),"sfg")))),w.names = c(NA,6L),class = "data.frame")
co_s <- st_coordinates(st_as_sfc(moves$start))
co_e <- st_coordinates(st_as_sfc(moves$end))
s_lon <- co_s[,"X"]
s_lat <- co_s[,"Y"]
e_lon <- co_e[,"X"]
e_lat <- co_e[,"Y"]
plot(c(s_lon,e_lon),c(s_lat,e_lat),col = rep(c("red","blue"),each = 6),pch = 20,cex = 2,xlab = "lon",ylab = "lat")
arrows(s_lon,s_lat,e_lon,e_lat)
很好的问题。抱歉，没有箭头。结果只有直线。为了回答这个问题，我需要将“运动”数据转换为两个矩阵对象：一个矩阵作为起点，第二个矩阵作为终点。
s_lon <- c(-2.030474,-2.319776,-2.025846,-2.426711,-2.116654,-2.122917)
s_lat <- c(51.36306,51.46162,51.47712,51.38076,51.4887,51.5861)
e_lon <- c(-2.250102,-2.491189,-2.063781,-2.132722,-2.204403,-2.134635)
e_lat <- c(51.41609,51.41029,51.49158,51.46999,51.51874,51.51806)
# Create matrixes from data
m_s <- matrix(data = c(s_lon,s_lat),nrow = 6,ncol = 2,byrow = FALSE)
m_e <- matrix(data = c(e_lon,byrow = FALSE)
然后使用循环将每个矩阵中的数据转换为简单特征几何点，并将每对（起点和终点）组合成一个列表。
然后绘制每对起点/终点以及连接它们的字符串。
n <- c(1:6)
myplotfct <- function(i,s1,e1,pt_s1.sfg,pt_e1.sfg,mylist) {
if(i == 1) {
plot(mylist,axes = TRUE,xlim = c(-2.5,-1.8),ylim = c(51.3,51.65),pch = 19,cex = 3,col = "red",)
ln1 <- st_nearest_points(pt_s1.sfg,pt_e1.sfg)
plot(ln1,add = TRUE)
} else {
plot(mylist,add = TRUE,col = "blue")
ln1 <- st_nearest_points(pt_s1.sfg,add = TRUE)
}
}
my_s <- function(n,.) { # Start Pt Function
m_s[n,]
}
my_e <- function(n,.) { # End Pt Function
m_e[n,]
}
for(i in 1:6) {
s1 <- my_s(i,m_s[x,]) # Fct call
e1 <- my_e(i,m_e[x,])
pt_s1.sfg <- st_point(x = c(s1),dim = "XY") # convert s1 to geometric
pt_e1.sfg <- st_point(x = c(e1),dim = "XY") # convert e1 to geometric
mylist <- c(pt_s1.sfg,pt_e1.sfg) # create a list of the two geometric points (start - end)
myplotfct(i,mylist)
}
如果需要，可以通过更改每对颜色来改善输出。可以从此link:
查看输出