[英]R ggplot2: draw multiple line segments connecting pairs of points on map
考虑具有多对点的地图。 使用ggplot2
,如何将每对点与线段相连?
考虑以下可重现的示例。
# Load libraries.
library(ggmap) # for getting map
library(ggplot2) # for plots
# Create data frame of points on the map.
data <- data.frame(p1 = c(1, 3, 5), p2 = c(2, 4, 6),
lat_p1 = c(37.78, 37.75, 37.73),
lon_p1 = c(-122.41, -122.40, -122.405),
lat_p2 = c(37.77, 37.75, 37.72),
lon_p2 = c(-122.43, -122.42, -122.415))
data
p1 p2 lat_p1 lon_p1 lat_p2 lon_p2
1 1 2 37.78 -122.410 37.77 -122.430
2 3 4 37.75 -122.400 37.75 -122.420
3 5 6 37.73 -122.405 37.72 -122.415
# Get map.
map <- get_map(location = c(left = -122.523, bottom = 37.69,
right = -122.35, top = 37.813),
maptype = "roadmap", source = "osm", color = "bw")
# Plot points on the map.
ggmap(map) +
geom_point(data = data, aes(x = lon_p1, y = lat_p1), color = "red",
size = 1) +
geom_point(data = data, aes(x = lon_p2, y = lat_p2), color = "purple",
size = 1)
特别是如何将图中的红色和紫色点与线段连接?
有几个相关的问题,它们使用geom_line()
通过多个点绘制单个线段。 但是,我还没有看到这样的帖子。
这是修改数据框以获得所需图形的解决方案。
# Load libraries (same as before).
library(ggmap) # for getting map
library(ggplot2) # for plots
# Modify the original data frame.
data2 <- data.frame(point = c(1, 3, 5, 2, 4, 6),
pair = c('A', 'B', 'C', 'A', 'B', 'C'),
color.group = c('foo', 'foo', 'foo', 'bar', 'bar', 'bar'),
lat = c(37.78, 37.75, 37.73, 37.77, 37.75, 37.72),
lon = c(-122.41, -122.40, -122.405, -122.43, -122.42, -122.415))
data2
point pair color.group lat lon
1 1 A foo 37.78 -122.410
2 3 B foo 37.75 -122.400
3 5 C foo 37.73 -122.405
4 2 A bar 37.77 -122.430
5 4 B bar 37.75 -122.420
6 6 C bar 37.72 -122.415
# Get map (same as before).
map <- get_map(location = c(left = -122.523, bottom = 37.69,
right = -122.35, top = 37.813),
maptype = "roadmap", source = "osm", color = "bw")
# Plot map with line segments.
ggmap(map) +
geom_point(data = data2, aes(x = lon, y = lat, color = color.group)) +
geom_line(data = data2, aes(x = lon, y = lat, group = pair))
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