r - Convert output from sf::st_within to vector

Question

Im trying to use the sf package in R to see if sf object is within another sf object with the st_within function. My issue is with the output of this function w

Answer 1

Instead of using the st_within function directly, try using a spatial join. Check out the following example how st_joins works

library(sf)
library(tidyverse)

lines <-
data.frame(id=gl(3,2), x=c(-3,2,6,11,7,10), y=c(-1,6,-5,-9,10,5)) %>%
  st_as_sf(coords=c("x","y"), remove=F) %>% 
  group_by(id) %>% 
  summarise() %>%
  st_cast("LINESTRING")

yta10 <-
    st_point(c(0, 0)) %>%
    st_buffer(dist = 10) %>%
    st_sfc() %>%
    st_sf(yta = "10m")

With a left join all lines are kept, but you can see which of them that are located inside the polygon

lines %>% st_join(yta10, left=TRUE)

An inner join (left = FALSE) only keeps the ones inside

lines %>% st_join(yta10, left=FALSE)

The latter can also be obtained by

lines[yta10,]