传单添加多段线
我见过类似的问题，但到目前为止没有一个符合我的需求（至少在我理解的范围内），所以如果这个问题已经得到解答，我会提前道歉。我也是一个 R 新手。
我有一个数据框，每行包含两组纬度/经度。实际数据包含数百行和许多列相关数据。我正在绘制两组纬度/经度的点，并希望将每对点连接为一条单独的线。下面是结果应该是什么样子的示例。
[![在此处输入图像描述][1]][1]
这是数据的简化示例。将有重复的事件和位置值。
Event_lat Event_lon Event Location Location_latitude Location_longitude
40.791151 -124.054008 704832643 60005 40.790961 -124.1825609
38.900882 -122.660353 704653051 60009 38.873889 -122.709722
38.921488 -122.600049 704681147 60011 38.85111099 -122.593333
38.921488 -122.600049 704681147 60011 38.85111099 -122.593333
39.141877 -123.044724 706777142 60012 39.22794396 -123.064722
38.928113 -122.611386 708644013 60016 38.98950003 -122.7695828
39.02361 -122.72195 708582623 60016 38.98950003 -122.7695828
38.87586 -122.842684 708336092 60016 38.98950003 -122.7695828
39.239926 -123.145497 709020144 60017 39.24138798 -123.2163878
39.3307 -123.221674 708875205 60017 39.24138798 -123.2163878
以下是映射点的代码的简化示例：
library(leaflet)
myData <-read.csv("Book1.csv",header=TRUE, sep=",")
leaflet()%>%
addTiles() %>%
addCircles(myData,lng = myData$lsr_lon,lat = myData$lsr_lat, radius=20, color = "red",group = "events") %>%
addCircles(myData,lng = myData$site_longitude,lat = myData$site_latitude, radius=20, color = "blue",group = 'Locations')
我提出了一个使用library(sf)and的解决方案library(data.table)，其中sf具有 superseed sp，并且data.table用于有效地重塑数据。
我在他们的解决方案中使用了 Wimpel 提供的数据。
重塑
创建sf对象相当简单。我们需要LINESTRING为数据的每一行（作为sfg对象）创建一个，然后转换为sf
library(sf)
library(data.table)
setDT(df)
## create an 'id' / index value. This assumes each row of your data is a separate line.
df[, idx := .I]
## create an `sfc` column (where each row is an `sfg` object)
sf <- df[
, {
geometry <- sf::st_linestring(x = matrix(c(Event_lon, Event_lat, Location_longitude, Location_latitude), ncol = 2, byrow = T))
geometry <- sf::st_sfc(geometry)
geometry <- sf::st_sf(geometry = geometry)
}
, by = idx
]
## convert to sf
sf <- sf::st_as_sf(sf)
绘图
有了这个sf对象，您现在可以在传单中绘制（使用与 Wimpel 类似的代码）
library(leaflet)
leaflet() %>%
addTiles() %>%
addPolylines(data = sf) %>%
addCircles(data = df, lng = ~Event_lon, lat = ~Event_lat, radius=20, color = "red", group = "events") %>%
addCircles(data = df, lng = ~Location_longitude, lat = ~Location_latitude, radius=20, color = "blue", group = 'Locations')
我自己刚刚开始使用 R 和传单，所以这可能不是解决这个问题的最有效方法。尽管如此，它对我来说工作得很好...随时欢迎反馈！
结果
样本数据
df <- read.table( text = "Event_lat Event_lon Event Location Location_latitude Location_longitude
40.791151 -124.054008 704832643 60005 40.790961 -124.1825609
38.900882 -122.660353 704653051 60009 38.873889 -122.709722
38.921488 -122.600049 704681147 60011 38.85111099 -122.593333
38.921488 -122.600049 704681147 60011 38.85111099 -122.593333
39.141877 -123.044724 706777142 60012 39.22794396 -123.064722
38.928113 -122.611386 708644013 60016 38.98950003 -122.7695828
39.02361 -122.72195 708582623 60016 38.98950003 -122.7695828
38.87586 -122.842684 708336092 60016 38.98950003 -122.7695828
39.239926 -123.145497 709020144 60017 39.24138798 -123.2163878
39.3307 -123.221674 708875205 60017 39.24138798 -123.2163878", header = TRUE)
代码
我想创建一个空间线对象，我可以用addPolylines.
首先，我想创建一个仅包含纬度/经度的 data.frame，每个id事件位置组合都有唯一的。
library(tidyverse)
#craete a column with unique id's per event-location combination
df <- df %>% mutate( id = row_number() )
#create a temporaty df with events
events.df <- df %>%
select( id, Event_lat, Event_lon) %>%
rename( latitude = Event_lat, longitude = Event_lon)
#create a temporaty df with locations
locations.df <- df %>%
select( id, Location_latitude, Location_longitude) %>%
rename( latitude = Location_latitude, longitude = Location_longitude)
#merge the two temp.df's together
df.sp <- bind_rows( events.df, locations.df )
# id latitude longitude
# 1 1 40.79115 -124.0540
# 2 2 38.90088 -122.6604
# 3 3 38.92149 -122.6000
# 4 4 38.92149 -122.6000
# 5 5 39.14188 -123.0447
# 6 6 38.92811 -122.6114
# 7 7 39.02361 -122.7220
# 8 8 38.87586 -122.8427
# 9 9 39.23993 -123.1455
# 10 10 39.33070 -123.2217
# 11 1 40.79096 -124.1826
# 12 2 38.87389 -122.7097
# 13 3 38.85111 -122.5933
# 14 4 38.85111 -122.5933
# 15 5 39.22794 -123.0647
# 16 6 38.98950 -122.7696
# 17 7 38.98950 -122.7696
# 18 8 38.98950 -122.7696
# 19 9 39.24139 -123.2164
# 20 10 39.24139 -123.2164
现在创建空间线对象
library(maptools)
library(sp)
#make df.sp a spatialdataframe
coordinates( df.sp ) <- c( "longitude", "latitude" )
#create a list per id
id.list <- sp::split( df.sp, df.sp[["id"]] )
#initialisation of counter
id <- 1
#for each id, create a line that connects all points with that id
for ( i in id.list ) {
event.lines <- SpatialLines( list( Lines( Line( i[1]@coords ), ID = id ) ),
proj4string = CRS( "+init=epsg:4326" ) )
if ( id == 1 ) {
sp_lines <- event.lines
} else {
sp_lines <- spRbind( sp_lines, event.lines )
}
id <- id + 1
}
查看。
head(sp_lines,1)
# An object of class "SpatialLines"
# Slot "lines":
# [[1]]
# An object of class "Lines"
# Slot "Lines":
# [[1]]
# An object of class "Line"
# Slot "coords":
# longitude latitude
# [1,] -124.0540 40.79115
# [2,] -124.1826 40.79096
#
# Slot "ID":
# [1] "1"
#
# Slot "bbox":
# min max
# x -124.18256 -124.05401
# y 40.79096 40.79115
#
# Slot "proj4string":
# CRS arguments:
# +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0
现在，在传单中绘制点和折线
library(leaflet)
leaflet()%>%
addTiles() %>%
addCircles(df,lng = df$Event_lon, lat = df$Event_lat, radius=20, color = "red", group = "events") %>%
addCircles(df,lng = df$Location_longitude, lat = df$Location_latitude, radius=20, color = "blue", group = 'Locations') %>%
addPolylines( data = sp_lines )