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.
