similar to: Bias in R's random integers?

On 19/09/2018 12:23 PM, Philip B. Stark wrote: > No, the 2nd call only happens when m > 2**31. Here's the code: Yes, you're right. Sorry! So the ratio really does come close to 2. However, the difference in probabilities between outcomes is still at most 2^-32 when m is less than that cutoff. That's not feasible to detect; the only detectable difference would happen if

On 19/09/2018 3:52 PM, Philip B. Stark wrote: > Hi Duncan-- > > Nice simulation! > > The absolute difference in probabilities is small, but the maximum > relative difference grows from something negligible to almost 2 as m > approaches 2**31. > > Because the L_1 distance between the uniform distribution on {1, ..., m} > and what you actually get is large, there

With reference to R News News: R version 3.0.0 (Masked Marvel) has been released on 2013-04-03. R version 2.15.3 (Security Blanket) has been released on 2013-03-01 R version 2.15.2 (Trick or Treat) .... R version 2.15.1 ("Roasted Marshmallows") ... R version 2.15.0 ("Easter Beagle") R version 2.14.0 ("Great Pumpkin") Dear R help List, How are these version types

For a well-tested C algorithm, based on my reading of Lemire, the unbiased "algorithm 3" in https://arxiv.org/abs/1805.10941 is part already of the C standard library in OpenBSD and macOS (as arc4random_uniform), and in the GNU standard library. Lemire also provides C++ code in the appendix of his piece for both this and the faster "nearly divisionless" algorithm. It would be

On 19/09/2018 5:57 PM, David Hugh-Jones wrote: > > It doesn't seem too hard to come up with plausible ways in which this > could give bad results. Suppose I sample rows from a large dataset, > maybe for bootstrapping. Suppose the rows are non-randomly ordered, e.g. > odd rows are males, even rows are females. Oops! Very non-representative > sample, bootstrap p values are

A quick point of order here: arguing with Duncan in this forum is helpful to expose ideas, but probably neither side will convince the other; eventually, if you want this adopted in core R, you'll need to convince an R-core member to pursue this fix. In the meantime, a good, well-tested implementation in a user-contributed package (presumably written in C for speed) would be enormously

Hi Duncan-- Nice simulation! The absolute difference in probabilities is small, but the maximum relative difference grows from something negligible to almost 2 as m approaches 2**31. Because the L_1 distance between the uniform distribution on {1, ..., m} and what you actually get is large, there have to be test functions whose expectations are quite different under the two distributions.

It doesn't seem too hard to come up with plausible ways in which this could give bad results. Suppose I sample rows from a large dataset, maybe for bootstrapping. Suppose the rows are non-randomly ordered, e.g. odd rows are males, even rows are females. Oops! Very non-representative sample, bootstrap p values are garbage. David On Wed, 19 Sep 2018 at 21:20, Duncan Murdoch <murdoch.duncan

No, the 2nd call only happens when m > 2**31. Here's the code: (RNG.c, lines 793ff) double R_unif_index(double dn) { double cut = INT_MAX; switch(RNG_kind) { case KNUTH_TAOCP: case USER_UNIF: case KNUTH_TAOCP2: cut = 33554431.0; /* 2^25 - 1 */ break; default: break; } double u = dn > cut ? ru() : unif_rand(); return floor(dn * u); } On Wed, Sep

Dear useR's, today I stumbled over an interesting phenomenon: First, I created a named numeric vector with a certain class and several attributes via the structure() function. After that, I implemented a simple print method for this class. When calling this function it produces an endless loop of print calls until R crashes. :/ What is going on here? Is this a bug or have I done something

Hi, Using R 2.15.1 on Windows 7. Have installed both versions 32 and 64bit. In both of them among others I have installed a package rgenoud When I open R gui of 32bit and write library(rgenoud) it responds by showing a functional rgenoud version 5.7-8. The same it does on Rgui 64bit. Now I am working in cygwin (v. 1.12.4.0) with xwin. Normally before when I had installed a package, I only had

( A similar problem is also reported by Sebastian P. Luque with library(maptools) library(trip) in the vignette as below ). I am writing a vignette which loads RMySQL and RPostgreSQL. This produces the warning: Loading required package: DBI Warning in .simpleDuplicateClass(def, prev) : A specification for class ?dbObjectId? in package ?RPostgreSQL? seems equivalent to one from package

Hi, I am trying to use the gettext() function to translate some text. I have never used this function before, so, it's entirely possible that I am doing something wrong. The issue that I am encountering is that gettext() properly translates some text, but not some other. Natural language was compiled in my R (installed from the Debian repositories): $ R R version 2.15.1 (2012-06-22) --

Hi, I am trying to use the gettext() function to translate some text. I have never used this function before, so, it's entirely possible that I am doing something wrong. The issue that I am encountering is that gettext() properly translates some text, but not some other. Natural language was compiled in my R (installed from the Debian repositories): $ R R version 2.15.1 (2012-06-22) --

I am installing R 2.15.1 onto RHEL 6, using gcc 4.7.0 with Intel MKL 10.3.7 and the following environment: export BLAS_LIBS="-Wl,--start-group /usr/caen/intel-12.1/mkl/lib/intel64/libmkl_gf_lp64.a /usr/caen/intel-12.1/mkl/lib/intel64/libmkl_sequential.a /usr/caen/intel-12.1/mkl/lib/intel64/libmkl_core.a -Wl,--end-group -lpthread" export LAPACK_LIBS="-Wl,--start-group

Hello, I spent a lot of a time on a weird bug, and I just managed to narrow it down. In parallel code (here with parallel::mclappy, but I got it doMC/multicore too), if the library(tcltk) is loaded, R hangs when trying to open a DB connection. I got the same behaviour on two different computers, one dual-core, and one 2 xeon quad-core. Here's the code: library(parallel) library(RSQLite)

Hello everyone im trying to install Rmpi library on centos 6. I have already installed mpich2 1.4 [root@localhost ~]# R --version > R version 2.15.1 (2012-06-22) -- "Roasted Marshmallows" > Copyright (C) 2012 The R Foundation for Statistical Computing > ISBN 3-900051-07-0 > Platform: x86_64-redhat-linux-gnu (64-bit) [root@localhost ~]# mpich2version > MPICH2 Version:

> ?prompt [SNIP] ## Create a help file for each function in the .GlobalEnv: for(f in ls()) if(is.function(get(f))) prompt(name = f) > foo <- function(x) { cat(x, '\n')} > prompt(name="foo") Error in utils:::prompt(object, filename = filename, name = name, ...) : argument "object" is missing, with no default > version platform

I have installed Sweave as recommended. http://lifeasclay.wordpress.com/tag/sweave/. Placing a test.Rnw file, for instance, in "/Library/Frameworks/R.framework/Versions/2.15/Resources/library/utils/Sweave" generates test.tex files that generate pdf files with LaTeX. To be honest, placing Rnw files seem to make sense. The "exams" package does require not this step. It uses

In help(gc) I read, "...the primary purpose of calling 'gc' is for the report on memory usage". What memory usage does gc() report? And more importantly, which memory uses does it NOT report? Because I see one answer from gc(): used (Mb) gc trigger (Mb) max used (Mb) Ncells 14875922 794.5 21754962 1161.9 17854776 953.6 Vcells 59905567 457.1 84428913 644.2