On Tue, Feb 20, 2018 at 11:58 AM, Bert Gunter <bgunter.4...@gmail.com> wrote:
> Ista, et. al: efficiency? > (Note: I needed to correct my previous post: do.call() is required for > pmax() over the data frame) > > > x <- data.frame(matrix(runif(12e6), ncol=12)) > > > system.time(r1 <- do.call(pmax,x)) > user system elapsed > 0.049 0.000 0.049 > > > identical(r1,r2) > [1] FALSE > > system.time(r2 <- apply(x,1,max)) > user system elapsed > 2.162 0.045 2.207 > > ## 150 times slower! > > > identical(r1,r2) > [1] TRUE > > pmax() is there for a reason. > Or is there something I am missing? > Personal preference I think. I prefer the consistency of apply. If speed is an issue matrixStats is both consistent and fast: library(matrixStats) x <- matrix(runif(12e6), ncol=12) system.time(r1 <- do.call(pmax,as.data.frame(x))) ## user system elapsed ## 0.109 0.000 0.109 system.time(r2 <- apply(x,1,max)) ## user system elapsed ## 1.292 0.024 1.321 system.time(r3 <- rowMaxs(x)) ## user system elapsed ## 0.044 0.000 0.044 pmax is a fine alternative for max special case. Best, Ista > > Cheers, > Bert > > > > Bert Gunter > > "The trouble with having an open mind is that people keep coming along and > sticking things into it." > -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > On Tue, Feb 20, 2018 at 8:16 AM, Miluji Sb <miluj...@gmail.com> wrote: > >> This is what I was looking for. Thank you everyone! >> >> Sincerely, >> >> Milu >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> >> Mail >> priva di virus. www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> >> <#m_4297398466082743447_m_6071581590498622123_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >> >> On Tue, Feb 20, 2018 at 5:10 PM, Ista Zahn <istaz...@gmail.com> wrote: >> >>> Hi Milu, >>> >>> byapply(df, 12, function(x) apply(x, 1, max)) >>> >>> You might also be interested in the matrixStats package. >>> >>> Best, >>> Ista >>> >>> On Tue, Feb 20, 2018 at 9:55 AM, Miluji Sb <miluj...@gmail.com> wrote: >>> > Dear all, >>> > >>> > I have monthly data in wide format, I am only providing data (at the >>> bottom >>> > of the email) for the first 24 columns but I have 2880 columns in >>> total. >>> > >>> > I would like to take max of every 12 columns. I have taken the mean of >>> > every 12 columns with the following code: >>> > >>> > byapply <- function(x, by, fun, ...) >>> > { >>> > # Create index list >>> > if (length(by) == 1) >>> > { >>> > nc <- ncol(x) >>> > split.index <- rep(1:ceiling(nc / by), each = by, length.out = nc) >>> > } else # 'by' is a vector of groups >>> > { >>> > nc <- length(by) >>> > split.index <- by >>> > } >>> > index.list <- split(seq(from = 1, to = nc), split.index) >>> > >>> > # Pass index list to fun using sapply() and return object >>> > sapply(index.list, function(i) >>> > { >>> > do.call(fun, list(x[, i], ...)) >>> > }) >>> > } >>> > >>> > ## Compute annual means >>> > y <- byapply(df, 12, rowMeans) >>> > >>> > How can I switch rowMeans with a command that takes the maximum? I am >>> a bit >>> > baffled. Any help will be appreciated. Thank you. >>> > >>> > Sincerely, >>> > >>> > Milu >>> > >>> > ### >>> > dput(droplevels(head(x, 5))) >>> > structure(list(X0 = c(295.812103271484, 297.672424316406, >>> 299.006805419922, >>> > 297.631500244141, 298.372741699219), X1 = c(295.361328125, >>> > 297.345092773438, >>> > 298.067504882812, 297.285339355469, 298.275268554688), X2 = >>> > c(294.279602050781, >>> > 296.401550292969, 296.777984619141, 296.089111328125, 297.540374755859 >>> > ), X3 = c(292.103118896484, 294.253601074219, 293.773803710938, >>> > 293.916229248047, 296.129943847656), X4 = c(288.525024414062, >>> > 291.274505615234, 289.502777099609, 290.723388671875, 293.615112304688 >>> > ), X5 = c(286.018371582031, 288.748565673828, 286.463134765625, >>> > 288.393951416016, 291.710266113281), X6 = c(285.550537109375, >>> > 288.159149169922, 285.976501464844, 287.999816894531, 291.228271484375 >>> > ), X7 = c(289.136962890625, 290.751159667969, 290.170257568359, >>> > 291.796203613281, 293.423248291016), X8 = c(292.410003662109, >>> > 292.701263427734, 294.25244140625, 295.320404052734, 295.248199462891 >>> > ), X9 = c(293.821655273438, 294.139068603516, 296.630157470703, >>> > 296.963531494141, 296.036224365234), X10 = c(294.532531738281, >>> > 295.366607666016, 297.677551269531, 296.715911865234, 296.564178466797 >>> > ), X11 = c(295.869476318359, 297.010070800781, 299.330169677734, >>> > 297.627593994141, 297.964935302734), X12 = c(295.986236572266, >>> > 297.675567626953, 299.056671142578, 297.598907470703, 298.481842041016 >>> > ), X13 = c(295.947601318359, 297.934448242188, 298.745391845703, >>> > 297.704925537109, 298.819091796875), X14 = c(294.654327392578, >>> > 296.722717285156, 297.0986328125, 296.508239746094, 297.822021484375 >>> > ), X15 = c(292.176361083984, 294.49658203125, 293.888305664062, >>> > 294.172149658203, 296.117095947266 <(709)%20594-7266>), X16 = >>> c(288.400726318359, >>> > 291.029113769531, 289.361907958984, 290.566772460938, 293.554016113281 >>> > ), X17 = c(285.665222167969, 288.293029785156, 286.118957519531, >>> > 288.105285644531, 291.429382324219), X18 = c(285.971252441406, >>> > 288.3798828125, 286.444580078125, 288.495880126953, 291.447326660156 >>> > ), X19 = c(288.79296875, 290.357543945312, 289.657928466797, >>> > 291.449066162109, 293.095275878906), X20 = c(291.999877929688, >>> > 292.838348388672, 293.840362548828, 294.412322998047, 294.941253662109 >>> > ), X21 = c(293.615447998047, 294.028106689453, 296.072296142578, >>> > 296.447387695312, 295.824615478516), X22 = c(294.719848632812, >>> > 295.392028808594, 297.453216552734, 297.114288330078, 296.883209228516 >>> > ), X23 = c(295.634429931641, 296.783294677734, 298.592346191406, >>> > 297.469512939453, 297.832122802734)), .Names = c("X0", "X1", >>> > "X2", "X3", "X4", "X5", "X6", "X7", "X8", "X9", "X10", "X11", >>> > "X12", "X13", "X14", "X15", "X16", "X17", "X18", "X19", "X20", >>> > "X21", "X22", "X23"), row.names = c(NA, 5L), class = "data.frame") >>> > >>> > <https://www.avast.com/sig-email?utm_medium=email&utm_source >>> =link&utm_campaign=sig-email&utm_content=webmail> >>> > Mail >>> > priva di virus. www.avast.com >>> > <https://www.avast.com/sig-email?utm_medium=email&utm_source >>> =link&utm_campaign=sig-email&utm_content=webmail> >>> > <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >>> > >>> > [[alternative HTML version deleted]] >>> > >>> > ______________________________________________ >>> > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >>> > https://stat.ethz.ch/mailman/listinfo/r-help >>> > PLEASE do read the posting guide http://www.R-project.org/posti >>> ng-guide.html >>> > and provide commented, minimal, self-contained, reproducible code. >>> >> >> > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
