Ah yes, my eternal nemesis the S4 class... You were basically there with
e[e$coordinates==(0,17),] but for some access stuff that comes from the SpatialDataPointsFrame class. You'll probably want to do this in two steps: coords = coordinates(e) ## Use the access function coordinates to get a 2xn matrix of coordinates x and y; ## you could also do this with coords = e@coords as Weidong noted but it's discouraged e[coords[,"x"] == my.x & coords[,"y"] == my.y, "leachate"] I can't test it on your data, but I think this will do it. data(meuse.grid) coordinates(meuse.grid) <- ~x+y M = meuse.grid coords = coordinates(M) M[(coords[,"x"] == 179220) & (coords[,"y"] == 329620), "soil"] Hope this helps, Michael On Thu, Oct 13, 2011 at 2:18 PM, Bailey, Daniel <bai...@spu.edu> wrote: > Michael, > Thank you for the tips. The suggestion didn't work though. Here is the output > of str(e): > Formal class 'SpatialPointsDataFrame' [package "sp"] with 5 slots > ..@ data :'data.frame': 168 obs. of 2 variables: > .. ..$ catchcandata: num [1:168] 47.2 50.4 53.7 58 69.8 ... > .. ..$ section : Factor w/ 1 level "16 Sept F9": 1 NA NA NA NA NA NA NA > NA NA ... > ..@ coords.nrs : int [1:2] 1 2 > ..@ coords : num [1:168, 1:2] 0 0 0 0 0 ... > .. ..- attr(*, "dimnames")=List of 2 > .. .. ..$ : NULL > .. .. ..$ : chr [1:2] "x" "y" > ..@ bbox : num [1:2, 1:2] 0 0 48.8 17.1 > .. ..- attr(*, "dimnames")=List of 2 > .. .. ..$ : chr [1:2] "x" "y" > .. .. ..$ : chr [1:2] "min" "max" > ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots > .. .. ..@ projargs: chr NA > > -----Original Message----- > From: R. Michael Weylandt [mailto:michael.weyla...@gmail.com] > Sent: Thursday, October 13, 2011 11:13 AM > To: Bailey, Daniel > Cc: Sarah Goslee; r-help@r-project.org > Subject: Re: [R] getting data associated with coordinates in a spatial data > frame > > It's going to depend how the coordinates are stored within the data frame. Do > you perhaps know if they are factors or character strings? > (I'm not familiar with the package). If you don't know, type > str(NAMEOFYOUROBJECT) and we can help interpret the output. > > Untested, I think this would actually work for both though: > e[as.character(e$coordinates)=="(0,17)",] > > Michael > > On Thu, Oct 13, 2011 at 2:05 PM, Bailey, Daniel <bai...@spu.edu> wrote: >> Thank you Sarah. I tried your suggestion, and if I coerce it into a normal >> data.frame, that method works. But if you've already made the data into a >> SpatialPixelsDataFrame and run coordinates (both from the package "sp") so >> that the columns "x" and "y" become a single column "coordinates" with the >> format (0, 17) for x and y, how do you then call or manipulate data at a >> specific location? >> >> The following: >> e[e$coordinates==(0,17),] >> Doesn't work. >> >> >> -----Original Message----- >> From: Sarah Goslee [mailto:sarah.gos...@gmail.com] >> Sent: Wednesday, October 12, 2011 5:34 PM >> To: Bailey, Daniel >> Cc: r-help@r-project.org >> Subject: Re: [R] getting data associated with coordinates in a spatial >> data frame >> >> Hi, >> >> On Wed, Oct 12, 2011 at 3:37 PM, Bailey, Daniel <bai...@spu.edu> wrote: >>> If I know the specific coordinate in a spatial data frame, how can I access >>> the data at that coordinate? >>> >>> My coordinates are labeled "x" and "y" in a data.frame "e". The data is in >>> column "leachate". >>> I want to say, basically: >>> e$leachate@coordinates(2,3<mailto:e$leachate@coordinates(2,3>). >> >> That's kind of mangled, but what about: >> >> e[e$x == my.x & e$y == my.y, "leachate"] >> >> (Depending on the form of your coordinates, you may also have to >> invoke FAQ 7.31.) >> >> Sarah >> >>> Thanks, Daniel >>> >> >> -- >> Sarah Goslee >> http://www.functionaldiversity.org >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
