Dear Ákos, Thank you so much for the swift reply! Your answer helped me to solve this issue perfectly. Have a great one!
叶翔 YE, Xiang THINKING SPATIALLY<http://www.linkedin.com/in/spatialyexiang>. Ph.D. in Spatial Statistics ________________________________ From: R-sig-Geo <r-sig-geo-boun...@r-project.org> on behalf of Bede-Fazekas Ákos <bfalevl...@gmail.com> Sent: Monday, June 24, 2024 2:25 To: r-sig-geo@r-project.org <r-sig-geo@r-project.org> Subject: Re: [R-sig-Geo] error occured when combining st_sample() with raster::extract() Dear Xiang, I guess that the reason for the error is that zion_points is an sf object, while sampled_sites is an sfc object. You should create a 0-column sf object from the sfc using function st_as_sf(). Please try the following code: extract(srtm, st_as_sf(sampled_sites)) HTH, Ákos __________ Ákos Bede-Fazekas Centre for Ecological Research, Hungary 2024. 06. 23. 19:24 keltezéssel, Xiang Ye via R-sig-Geo írta: > Dear community, > > I am exploring the functionality of raster package by following the online > textbook Geocomputation with R, 1st ed. (I know the newer version of the > textbook is online, I just want to finish what I left). The problem I > encountered is associated with the example from Section 5.4.2, raster > extraction: > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbookdown.org%2Frobinlovelace%2Fgeocompr%2Fgeometric-operations.html%23raster-extraction&data=05%7C02%7Cxiangye%40buffalo.edu%7Cb2edba793f3d475bd6c108dc93b1ec03%7C96464a8af8ed40b199e25f6b50a20250%7C0%7C0%7C638547639583101457%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=D7s8aHWKp3D%2FOtHtBbP5m2Yc%2BXbkzFFqV3zYChIJQd8%3D&reserved=0<https://bookdown.org/robinlovelace/geocompr/geometric-operations.html#raster-extraction> > When I want to combine it with st_sample() from Section 5.2.3, i.e. extract > the pixel values from say 15 randomly chosen locations, I met an error. > > Here comes the script: > > library(sf) > library(raster) > > filename=system.file('raster/srtm.tif', package='spDataLarge') > srtm=raster(filename) > filename=system.file('vector/zion.gpkg', package='spDataLarge') > zion=st_read(filename) > zion=st_transform(zion, projection(srtm)) > > data('zion_points', package='spDataLarge') > extract(srtm, zion_points) # textbook example, work as expected > > sampled_sites=st_sample(zion, 15) > extract(srtm, sampled_sites) # error occurred. > > The error message says "����: ������extract����ǩ��x = "RasterLayer", y = > "sfc_POINT"���Ҳ����̳з���" > There is Chinese text embedded because my OS is in Chinese. Translated into > English, it reads "ERROR: function 'extract' labelling ��x = "RasterLayer", y > = "sfc_POINT"�� cannot find the inherited methods". > > My question: what's the reason of this problem, and how to fix it? > > Thank you in advance! > > Ҷ�� YE, Xiang > THINKING > SPATIALLY<https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.linkedin.com%2Fin%2Fspatialyexiang&data=05%7C02%7Cxiangye%40buffalo.edu%7Cb2edba793f3d475bd6c108dc93b1ec03%7C96464a8af8ed40b199e25f6b50a20250%7C0%7C0%7C638547639583112207%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=JAsnBDapAm4NYJb6zN5zdpralWRhHD1HA0M46sgwsQ4%3D&reserved=0<http://www.linkedin.com/in/spatialyexiang>>. > Ph.D. in Spatial Statistics > > [[alternative HTML version deleted]] > > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstat.ethz.ch%2Fmailman%2Flistinfo%2Fr-sig-geo&data=05%7C02%7Cxiangye%40buffalo.edu%7Cb2edba793f3d475bd6c108dc93b1ec03%7C96464a8af8ed40b199e25f6b50a20250%7C0%7C0%7C638547639583115271%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=FQ04KwpzFewolFlX0%2B6rufWKda6jBlcFYugRiiN4N%2BQ%3D&reserved=0<https://stat.ethz.ch/mailman/listinfo/r-sig-geo> _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstat.ethz.ch%2Fmailman%2Flistinfo%2Fr-sig-geo&data=05%7C02%7Cxiangye%40buffalo.edu%7Cb2edba793f3d475bd6c108dc93b1ec03%7C96464a8af8ed40b199e25f6b50a20250%7C0%7C0%7C638547639583118082%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=9OB10OER9p16VLRylMER5KlbA%2F7fwN11eEBbFYztkWc%3D&reserved=0<https://stat.ethz.ch/mailman/listinfo/r-sig-geo> [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
