R ggplot connecting one point on a map with multiple points on the same map

问题

I am trying to connect one location on the map of the US with multiple locations on the map of the US.

library(tidyverse)
library(flights13)

First, I am selecting all flights from Newark airport (EWR) on January 1, 2013 and grabbing the geographic coordinates for the destinations (if available in the tibble airports - and add EWR's location on top):

ewr <- flights %>% 
         filter(year== 2013, month== 1, day== 1, origin== "EWR") %>%  
         select(dest) %>% 
         distinct(dest) %>% 
         arrange(dest)

# Join it with airports database, add column "origin" filled with EWR:
mydest <- ewr %>% 
            left_join(select(airports, faa, lat, lon), 
                      by = c("dest" = "faa")) %>%
            filter(!is.na(lat)) %>% 
            select(lat, lon)
mydest

# Grab EWR coords:
ewrcoords <- airports %>% 
               filter(faa == "EWR") %>% 
               select(lat, lon)
ewrcoords
mydest <- rbind(ewrcoords, mydest)

Then, I want to connect the EWR (Newark) location with all the destination locations. I tried to do it using a loop, but it's not working inside ggplot:

mydest %>% 
  ggplot(aes(lon, lat)) +
  borders("state") +
  geom_point() +
  coord_quickmap() %>%
  for(i in 2:nrow(mydest)) {
    geom_line(data = mydest[c(1,i),], aes(lon, lat), 
              color = "black", size = 1)
  }

Is it possible to do it without a loop? Or how could I make the loop work? Thank you very much!

回答1:

Try this:

colnames(ewrcoords) = c("EWRlat", "EWRlon")
mydest <- cbind(ewrcoords, mydest)

mydest %>% 
  ggplot(aes(lon, lat)) +
  borders("state") +
  geom_point() +
  geom_segment(aes(y=EWRlat, x=EWRlon, xend=lon, yend=lat))+
  coord_quickmap()

EDIT: sorry did not see it was already in the comment by eipi10.

来源：https://stackoverflow.com/questions/46158896/r-ggplot-connecting-one-point-on-a-map-with-multiple-points-on-the-same-map

标签

ggplot2

tidyverse