quick question, i am trying to get an interval of values now with this code by toggling the tolerance limit. is there any way i can modify this code to find values which are within limits of BOTH latitude and longitude? currently i have to pick one or the other.
On Tue, Jul 28, 2009 at 9:29 AM, Mehdi Khan <mkhan...@gmail.com> wrote: > all right thank you! this was big help. > > > On Tue, Jul 28, 2009 at 2:22 AM, Martin Maechler < > maech...@stat.math.ethz.ch> wrote: > >> >>>>> "BertG" == Bert Gunter <gunter.ber...@gene.com> >> >>>>> on Mon, 27 Jul 2009 15:30:08 -0700 writes: >> >> BertG> Nothing wrong with rolling your own, but see >> BertG> ?all.equal for R's built-in "almost.equal" version. >> >> Yes, indeed! Note that that needs a little extra care, as it >> either returns TRUE or a character vector. >> In sum, I'd strongly suggest you use >> >> %~% <- function(x,y) isTRUE(all.equal(x,y)) >> >> Martin Maechler, ETH Zurich and R Core Team >> >> BertG> Bert Gunter Genentech Nonclinical Biostatistics >> >> BertG> -----Original Message----- From: >> BertG> r-help-boun...@r-project.org >> BertG> [mailto:r-help-boun...@r-project.org] On Behalf Of >> BertG> Steve Lianoglou Sent: Monday, July 27, 2009 3:17 PM >> BertG> To: Mehdi Khan Cc: r-help@r-project.org Subject: Re: >> BertG> [R] Searching for specific values in a matrix >> >> BertG> Ahh .. >> >> BertG> On Jul 27, 2009, at 6:01 PM, Mehdi Khan wrote: >> >> >> Even when choosing a value from the first few rows, it >> >> doesn't work. okay here it goes: >> >> >> >> > rearranged[1:10, 1:5] x y band1 VSCAT.001 soiltype 1 >> >> -124.3949 40.42468 NA NA CD 2 -124.3463 40.27358 NA NA CD >> >> 3 -124.3357 40.25226 NA NA CD 4 -124.3663 40.40241 NA NA >> >> CD 5 -124.3674 40.49810 NA NA CD 6 -124.3083 40.24744 NA >> >> 464 <NA> 7 -124.3017 40.31295 NA NA D 8 -124.3375 >> >> 40.47557 NA 464 <NA> 9 -124.2511 40.11697 1 NA <NA> 10 >> >> -124.2532 40.12640 1 NA <NA> >> >> >> >> > query<- rearranged$y== 40.42468 > rearranged[query,] >> >> [1] x y band1 VSCAT.001 soiltype <0 rows> (or 0-length >> >> row.names) >> >> BertG> This isn't working because the numbers you see for y >> BertG> (40.42468) isn't precisely what that number is. As I >> BertG> mentioned before you should use an "almost.equals" >> BertG> type of search for this scenario. My "%~%" function >> BertG> isn't working in your session because that is a >> BertG> function I've defined myself. You can of course use >> BertG> it, you just have to define it in your >> BertG> workspace. Paste these lines into your workspace (or >> BertG> save them to a file and "source" that file into your >> BertG> workspace). >> >> BertG> ## === almost.equal functions ==== >> >> BertG> almost.equal <- function(x, y, >> BertG> tolerance=.Machine$double.eps^0.5) { abs(x - y) < >> BertG> tolerance } >> >> BertG> "%~%" <- function(x, y) almost.equal(x, y) >> >> BertG> ## === end paste ============== >> >> BertG> Now you can use %~% once that's in. Let's use the >> BertG> almost.equal function now because I don't know if the >> BertG> default tolerance here is too strict (I suspect >> BertG> showing the value for rearranged$y[1] will show you >> BertG> more significant digits than you're seeing in the >> BertG> table(?)) >> >> BertG> query <- almost.equal(rearranged$y, 40.42468, >> BertG> tolerance=0.0001) rearranged[query,] >> >> BertG> This will get you something. >> >> >> query<- rearranged$ VSCAT.001== 464 except it's a huge >> >> table (I guess I have to get rid of all rows with NA). >> >> BertG> Yes, I believe I mentioned earlier that you have to >> BertG> axe the NA matches manually: >> >> BertG> query <- rearranged$VSCAT.001 == 464 & >> BertG> !is.na(rearranged$VSCAT.001) rearranged[query,] >> >> BertG> Will get you what you want. >> >> >> I tried using the %~% but R doesn't recognize it. So >> >> maybe it has to do with the rounding errors? >> >> BertG> Rounding errors won't happen with integer comparisons >> BertG> (and it looks like the VSCAT.001 columns is integers, >> BertG> no?). >> >> BertG> -steve >> >> BertG> -- Steve Lianoglou Graduate Student: Computational >> BertG> Systems Biology | Memorial Sloan-Kettering Cancer >> BertG> Center | Weill Medical College of Cornell University >> BertG> Contact Info: >> http://cbio.mskcc.org/~lianos/contact<http://cbio.mskcc.org/%7Elianos/contact> >> >> BertG> ______________________________________________ >> BertG> R-help@r-project.org mailing list >> BertG> https://stat.ethz.ch/mailman/listinfo/r-help PLEASE >> BertG> do read the posting guide >> BertG> http://www.R-project.org/posting-guide.html and >> BertG> provide commented, minimal, self-contained, >> BertG> reproducible code. >> >> BertG> ______________________________________________ >> BertG> R-help@r-project.org mailing list >> BertG> https://stat.ethz.ch/mailman/listinfo/r-help PLEASE >> BertG> do read the posting guide >> BertG> http://www.R-project.org/posting-guide.html and >> BertG> provide commented, minimal, self-contained, >> BertG> reproducible code. >> > > [[alternative HTML version deleted]] ______________________________________________ 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.
