st_join does a spatial join, which comes at a cost; since st_extract
doesn't change the row order of the sf object, you could as well use
st_extract(st1, sf1) %>% mutate(nums = sf1$nums)
On 03/02/2021 17:10, Julian M. Burgos wrote:
Dear list,
What would be the best way to do a spatial join between a sf object (of POINT
geometry) and a star object, so the sf object gets the values of the
corresponding pixels in the star object? I have done using a combination of
st_join and st_extract, but it feels a bit clunky. Is there a better way?
Here is what I have done:
## --------------------------------------------------------------
## Load a stars object
st1 <- read_stars(system.file("tif/L7_ETMs.tif", package = "stars")) %>%
slice(band, 1)
## Create an sf object
set.seed(100)
bb <- st_bbox(st1)
sf1 <- tibble(lon = runif(n = 10, min = bb[1], max = bb[3]),
lat = runif(n = 10, min = bb[2], max = bb[4]),
nums = 1:10) %>%
st_as_sf(coords = c("lon", "lat"), crs = st_crs(st1))
## Do the spatial join
sf1 <- st_extract(st1, sf1) %>%
st_join(sf1)
## --------------------------------------------------------------
Thanks,
Julian
--
Julian Mariano Burgos, PhD
Hafrannsóknastofnun, rannsókna- og ráðgjafarstofnun hafs og vatna/
Marine and Freshwater Research Institute
Botnsjávarsviðs / Demersal Division
Fornubúðir 5, IS-220 Hafnarfjörður, Iceland
www.hafogvatn.is
Sími/Telephone : +354-5752037
Netfang/Email: [email protected]
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