[R-sig-Geo] Spatial joins between sf and stars objects

[Julian M. Burgos]

Although if I use bind_cols the result is not an sf object....

Julian M. Burgos writes:

> Thanks Edzer, I should have checked if st_extract kept the order of the rows. In this case, a way to do it more generally is:
>
> sf1 <- bind_cols(st_drop_geometry(sf1),
>                  st_extract(st1, sf1))
>
>
>
> Edzer Pebesma writes:
>
>> 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
>>> http://www.hafogvatn.is/
>>> Sími/Telephone : +354-5752037
>>> Netfang/Email: julian.burgos using hafogvatn.is
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo using r-project.org
>>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstat.ethz.ch%2Fmailman%2Flistinfo%2Fr-sig-geo&data=04%7C01%7C%7C7b9230c283dd4883458a08d8c876e7d1%7C8e105b94435e4303a61063620dbe162b%7C0%7C0%7C637479760450605041%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=d%2FY%2FuSVIou5juUoKgSwCZc4EZ5OdEJRCg1YZHH%2FEYGc%3D&reserved=0
>>>
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo using r-project.org
>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstat.ethz.ch%2Fmailman%2Flistinfo%2Fr-sig-geo&data=04%7C01%7C%7C7b9230c283dd4883458a08d8c876e7d1%7C8e105b94435e4303a61063620dbe162b%7C0%7C0%7C637479760450605041%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=d%2FY%2FuSVIou5juUoKgSwCZc4EZ5OdEJRCg1YZHH%2FEYGc%3D&reserved=0


--
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: julian.burgos using hafogvatn.is