Displaying 20 results from an estimated 400 matches similar to: "Extreme bunching of random values from runif with Mersenne-Twister seed"
2017 Nov 03
2
Extreme bunching of random values from runif with Mersenne-Twister seed
Bill,
I have clarified this on SO, and I will copy that clarification in here:
"Sure, we tested them on other 8-digit numbers as well & we could not
replicate. However, these are honest-to-goodness numbers generated by a
non-adversarial system that has no conception of these numbers being used
for anything other than a unique key for an entity -- these are not a
specially constructed
2017 Nov 03
1
Extreme bunching of random values from runif with Mersenne-Twister seed
Martin,
Thanks for the helpful reply. Alas I had forgotten that (implied)
unfavorable comparisons of *nix systems with Windows systems would likely
draw irate (but always substantive) responses on the R-devel list -- poor
phrasing on my part. :)
Regardless, let me try to address some of the concerns related to the
construction of the MRE itself and try to see if we can clean away the
shrubbery
2017 Nov 03
2
Extreme bunching of random values from runif with Mersenne-Twister seed
Bill,
Appreciate the point that both you and Serguei are making, but the sequence
in question is not a selected or filtered set. These are values as observed
in a sequence from a mechanism described below. The probabilities required
to generate this exact sequence in the wild seem staggering to me.
T
On Fri, Nov 3, 2017 at 11:27 PM, William Dunlap <wdunlap at tibco.com> wrote:
>
2017 Nov 03
0
Extreme bunching of random values from runif with Mersenne-Twister seed
The random numbers in a stream initialized with one seed should have about
the desired distribution. You don't win by changing the seed all the
time. Your seeds caused the first numbers of a bunch of streams to be
about the same, but the second and subsequent entries in each stream do
look uniformly distributed.
You didn't say what your 'upstream process' was, but it is easy to
2017 Nov 03
0
Extreme bunching of random values from runif with Mersenne-Twister seed
Another other generator is subject to the same problem with the same
probabilitiy.
> Filter(function(s){set.seed(s,
kind="Knuth-TAOCP-2002");runif(1,17,26)>25.99}, 1:10000)
[1] 280 415 826 1372 2224 2544 3270 3594 3809 4116 4236 5018 5692 7043
7212 7364 7747 9256 9491 9568 9886
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Fri, Nov 3, 2017 at 10:31 AM, Tirthankar
2017 Nov 03
0
Extreme bunching of random values from runif with Mersenne-Twister seed
>>>>> Tirthankar Chakravarty <tirthankar.lists at gmail.com>
>>>>> on Fri, 3 Nov 2017 13:19:12 +0530 writes:
> This is cross-posted from SO
> (https://stackoverflow.com/q/47079702/1414455), but I now
> feel that this needs someone from R-Devel to help
> understand why this is happening.
Why R-devel -- R-help would have been
2017 Nov 05
0
Extreme bunching of random values from runif with Mersenne-Twister seed
Tirthankar,
"random number generators" do not produce random numbers. Any given
generator produces a fixed sequence of numbers that appear to meet
various tests of randomness. By picking a seed you enter that sequence
in a particular place and subsequent numbers in the sequence appear to
be unrelated. There are no guarantees that if YOU pick a SET of seeds
they won't produce
2012 Jul 16
1
problem with installing R pacakges
Dear R- Users,
I am unable to install R packages over the internet. Below is my session
information. My guess is that this may be
a proxy issue. I have set the http_proxy_user : my user id(network id) :
password (machine password) .
The error I get is as below
> install.packages("MASS")
Warning: unable to access index for repository
2010 Jul 13
2
Zoo - bug ???
Hi folks,
I am confused whether the following is a bug or it is fine
Here is the explanation
a <- zoo(c(NA,1:9),1:10)
Now If I do
rollapply(a,FUN=mean,width=3,align="right")
I get
> rollapply(a,FUN=mean,width=3,align="right")
3 4 5 6 7 8 9 10
NA NA NA NA NA NA NA NA
But I shouldn't be getting NA right ? i.e for index 10 I should get
(1/3)*(9+8+7)
2005 Jul 26
3
Generating unique random tokens for ActiveRecord objects
I have an ActiveRecord subclass that needs to generate a random (hard
to guess) token for each record in its corresponding table. Currently
I''m doing something like this:
def before_create
self[''token''] = random_value
while self.class.find_by_token(self[''token''])
self[''token''] = random_value
2017 Nov 04
0
Extreme bunching of random values from runif with Mersenne-Twister seed
In the code below, you seem to be essentially using the random number
generator to implement a hash function. This isn't a good idea.
My impression is that pseudo-random number generation methods are
generally evaluated by whether the sequence produced from any seed
"appears" to be random. Informally, there may be some effort to make
long sequences started with seeds 1, 2, 3, etc.
2010 Jun 02
0
Multiple threads writing to the same Starling queue doesn't work?
Hi guys,
I can''t find a clear answer to this: is it possible/correct to have
several threads write to the same Starling queue at the "same time"?
It doesn''t seem reliable according to my tests - but maybe I am doing
something wrong.
If I do:
def test_starling
FooWorker.asynch_foo_test(:my_id => ''foo'')
temp = []
for i in 1..1000
temp
2017 Nov 05
5
Extreme bunching of random values from runif with Mersenne-Twister seed
On 04/11/2017 10:20 PM, Daniel Nordlund wrote:
> Tirthankar,
>
> "random number generators" do not produce random numbers. Any given
> generator produces a fixed sequence of numbers that appear to meet
> various tests of randomness. By picking a seed you enter that sequence
> in a particular place and subsequent numbers in the sequence appear to
> be unrelated.
2006 Mar 14
2
Date problem
Hello,
I have some "stupid" problems managing "date" data.
I have a colomn "date", which I converted from a character representation:
for example:
a="26/02/06"
date=strptime(a,format="%d/%m/%y")
For one part of the analysis, I'm interested only in the month and the
year, so I did:
m.y=strftime(date,format="%m/%y")
This returns me
2004 Oct 21
5
Cluster Analysis: Density-Based Method
Hi people,
Does anybody know some Density-Based Method for clustering implemented in R?
Thanks,
Fernando Prass
_______________________________________________________
2006 Nov 06
2
Samba 3.0.10 / Solaris 8 / Windows 2003
Any help would be very much appreciated.
My Configuration-
Solaris 8 - hostname = vail
Samba 3.0.10 (downloaded from sunfreeware.com)
As per the instructions on sunfreeware, I have also installed the
following packages-
libgcc-3.3
libiconv-1.9.2
libintl-3.4.0
ncurses-5.4
popt 1.7
readline 5.1
Also on my network-
A Windows 2003 ES domain controller: hostname = SEEDS1 domain = SEEDS
A Windows
2012 Feb 17
3
portable parallel seeds project: request for critiques
I've got another edition of my simulation replication framework. I'm
attaching 2 R files and pasting in the readme.
I would especially like to know if I'm doing anything that breaks
.Random.seed or other things that R's parallel uses in the
environment.
In case you don't want to wrestle with attachments, the same files are
online in our SVN
2011 Dec 26
2
Zero-inflated Negative Binomial Error
Hello,
I am having a problem with the zero-inflated negative binomial (package
pscl). I have 6 sites with plant populations, and I am trying to model the
number of seeds produced as a function of their size and their site. There
are a lot of zero's because many of my plants get eaten before flowering,
thereby producing 0 seeds, and that varies by site. Because of that and
because the
2011 Feb 04
1
Easy help with plots, font size
I am trying to make some plots for a poster. Each one needs to be 6 inches by
inches. Right now the fonts are too small and the plots don't read well on
my poster. I am pretty much an R newbie and I can't figure out how to change
the fonts. It would also be nice to know how to specify the size of the plot
and maybe how to save the plots as jpeg files. Any help would be much
appreciated! I
2006 Oct 25
3
simplification of code using stamp?
Hi
I have the following code which I would like to simplify. Id does linear
regressions and returns the r-squares, and the coefficients.
It runs slow, as it is doing the regressions for each - is it possible
to get the values in a dataframe which looks as follow:
expert | xx | seeds | r.squared | slope | intercept
Thanks in advance,
Rainer
library(reshape)
rsqs <- as.data.frame(