similar to: simple questions about R

Displaying 20 results from an estimated 300 matches similar to: "simple questions about R"

2009 May 12
4
different results on linux and windows
Dear R experts, we are preparing an R-package to compute the Oja Median which contains some C++ code in which random numbers are needed. To generate the random numbers we use the following Mersenne-Twister implementation: // MersenneTwister.h // Mersenne Twister random number generator -- a C++ class MTRand // Based on code by Makoto Matsumoto, Takuji Nishimura, and Shawn Cokus // Richard J.
2016 Aug 30
4
A bug in the R Mersenne Twister (RNG) code?
Whomever, I recently sent the "bug report" below toR-core at r-project.org and have just been asked to instead submit it to you. Although I am basically not an R user, I have installed version 3.3.1 and am also the author of a statistics program written in Visual Basic that contains a component which correctly implements the Mersenne Twister (MT) algorithm. I believe that it is
2019 Feb 26
2
bias issue in sample() (PR 17494)
Gabe As mentioned on Twitter, I think the following behavior should be fixed as part of the upcoming changes: R.version.string ## [1] "R Under development (unstable) (2019-02-25 r76160)" .Machine$double.digits ## [1] 53 set.seed(123) RNGkind() ## [1] "Mersenne-Twister" "Inversion"??????? "Rejection" length(table(runif(1e6))) ## [1] 999863 I don't
2016 Aug 31
1
A bug in the R Mersenne Twister (RNG) code?
On 30 August 2016 at 18:29, Duncan Murdoch wrote: | I don't see evidence of a bug. There have been several versions of the | MT; we may be using a different version than you are. Ours is the | 1999/10/28 version; the web page you cite uses one from 2002. | | Perhaps the newer version fixes some problems, and then it would be | worth considering a change. But changing the default RNG
2016 Sep 01
2
A bug in the R Mersenne Twister (RNG) code?
On 08/30/2016 06:29 PM, Duncan Murdoch wrote: > I don't see evidence of a bug. There have been several versions of the > MT; we may be using a different version than you are. Ours is the > 1999/10/28 version; the web page you cite uses one from 2002. > > Perhaps the newer version fixes some problems, and then it would be > worth considering a change. But changing the
2005 Dec 15
1
precision of rnorm
How many distinct values can rnorm return? I assume that rnorm manipulates runif in some way, runif uses the Mersenne Twister, which has a period of 2^19937 - 1. Given that runif returns a 64 bit precision floating point number in [0,1], the actual period of the Mersenne Twister in a finite precision world must be significantly less. One of the arguments for Monte Carlo over the bootstrap is
2013 Feb 18
2
Random number generator used in 'runif'
Dear list, For the implementation of a particular optimization algorithm it is very important the random number generator. I would like to know if somebody could tell me what is the random number generator used by default in the 'runif' function. >From the help page of 'runif' and '.Random.seed' I guess that the default algorithm is 'Mersenne-Twister', but I
2011 Aug 05
2
Question on RNG
Hi all, I have happened to work on MS .NET for sometime now, and I found that this language offers RNG what is called as Donald E. Knuth's subtractive random number generator algorithm (found here: http://msdn.microsoft.com/en-us/library/system.random.aspx#Y12). ? Here I was wondering whether R also have same RNG in it's inventory, so looked at ?set.seed. There I found 2 related RNGs
2009 Jul 30
3
user supplied random number generators
?Random.user says (in svn trunk) Optionally, functions \code{user_unif_nseed} and \code{user_unif_seedloc} can be supplied which are called with no arguments and should return pointers to the number of seeds and to an integer array of seeds. Calls to \code{GetRNGstate} and \code{PutRNGstate} will then copy this array to and from \code{.Random.seed}. And it offers as an example void
2011 Feb 02
4
testing randomness of random number generators with student t-test?
Hi, subject more or less says it all. I freely admit to not having bothered to find some of the online papers about method of testing the quality of random number generators -- but in an idle moment I wondered what to expect from something like the following: randa<-runif(1000) randb<-runif(1000) t.test(randa,randb)$p.value var.test(randa,randb)$p.value [repeat ad nauseum] Is the
2019 Feb 19
2
bias issue in sample() (PR 17494)
Before the next release we really should to sort out the bias issue in sample() reported by Ottoboni and Stark in https://www.stat.berkeley.edu/~stark/Preprints/r-random-issues.pdf and filed aa a bug report by Duncan Murdoch at https://bugs.r-project.org/bugzilla/show_bug.cgi?id=17494. Here are two examples of bad behavior through current R-devel: set.seed(123) m <- (2/5) * 2^32
1997 Dec 02
2
R-beta: wish: hist() returning breaks and counts
Hi, would it be possible to change the hist() function in future R Versions to accept a "plot=F" parameter (like hist() in S it should return a list with "breaks" and "counts" in this case). This change should be very simple. Albrecht ------------------------------------------------------------------------------- Albrecht Gebhardt email :
1997 Dec 02
2
R-beta: wish: hist() returning breaks and counts
Hi, would it be possible to change the hist() function in future R Versions to accept a "plot=F" parameter (like hist() in S it should return a list with "breaks" and "counts" in this case). This change should be very simple. Albrecht ------------------------------------------------------------------------------- Albrecht Gebhardt email :
2019 Feb 26
1
bias issue in sample() (PR 17494)
Ralf I don't doubt this is expected with the current implementation, I doubt the implementation is desirable. Suggesting to turn this to pbirthday(1e6, classes = 2^53) ## [1] 5.550956e-05 (which is still non-zero, but much less likely to cause confusion.) Best regards Kirill On 26.02.19 10:18, Ralf Stubner wrote: > Kirill, > > I think some level of collision is actually
2003 Oct 20
1
Random Number Generator RNGkind() under "R CMD check" (PR#4691)
Full_Name: Wolfgang Huber Version: 1.8.0 OS: Linux Submission from: (NULL) (193.174.58.146) The man page for RNGkind says that the default is Mersenne-Twister, and when I start R interactively, I get in fact > RNGkind() [1] "Mersenne-Twister" "Inversion" However, during the execution of "R CMD check" I get > > ### ** Examples > > > > RNGkind()
2006 Sep 25
1
Initialising Mersenne-Twister with one integer
Hi, It seems to me that the Mersenne-Twister PRNG can be initialised using one integer instead of 624 integers, since inside RNG.c code there's a function defined as MT_sgenrand(Int32). How do I actually set this seed within R? I've tried: > .Random.seed <- c(3, 1) > runif(1) Error in runif(1) : .Random.seed has wrong length In addition, is '3' actually the
2008 Aug 17
1
Wichmann-Hill Random Number Generator and the Birthday Problem
Dear all, Recently I am generating large random samples (10M) and any duplicated numbers are not desired. We tried several RNGs in R and found Wichmann-Hill did not produce duplications. The duplication problem is the interesting birthday problem. If there are M possible numbers, randomly draw N numbers from them, the average number of dupilcations D = N(N-1)/2/M. For Knuth-TAOCP and
2013 Feb 21
1
limitations to random number generator in 64-bits machines
Dear List, Recently I got the comment that the implementation of the random number generator used by default in R (Mersenne-Twister) could not be "safe" for 64-bits machines, so I decided to put the question here because I do not have expertise in that topic, and because this question could be "too technical for R-help's audience". I apologise if this is not the case.
2005 Nov 17
2
R questions
Dear Sir/Madam, I am a beginner in R. Here is my questions. 1. Can you give me one test for randomness (a name and descriptive paragraph is sufficient). 2. I have learned a uniform random number generator [e.g. not the algorithms: i)Wichmann-Hill, ii) Marsaglia-Multicarry, iii) Super-Duper (Marsaglia), iv) Mersenne-Twister, v) TAOCP-1997 (Knuth), or vi) TAOCP-2002 (Knuth)] . Is there any other
2005 Dec 21
2
Random numbers
Hi All. I have R code whose functionality is being replicated within a C+ program. The outputs are to be compared to validate the conversion somewhat - however (as is always the case) I have stuffed my code with random number calls. Random uniform numbers in C+ are being produced using the (Boost) mersenne-twister generators (mt11213b & mt19937) - which is the default type of generator