Tirthankar Chakravarty
2017-Nov-03 07:49 UTC
[Rd] Extreme bunching of random values from runif with Mersenne-Twister seed
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.
We are facing a weird situation in our code when using R's [`runif`][1] and
setting seed with `set.seed` with the `kind = NULL` option (which resolves,
unless I am mistaken, to `kind = "default"`; the default being
`"Mersenne-Twister"`).
We set the seed using (8 digit) unique IDs generated by an upstream system,
before calling `runif`:
seeds = c(
"86548915", "86551615", "86566163",
"86577411", "86584144",
"86584272", "86620568", "86724613",
"86756002", "86768593",
"86772411",
"86781516", "86794389", "86805854",
"86814600", "86835092",
"86874179",
"86876466", "86901193", "86987847",
"86988080")
random_values = sapply(seeds, function(x) {
set.seed(x)
y = runif(1, 17, 26)
return(y)
})
This gives values that are **extremely** bunched together.
> summary(random_values)
Min. 1st Qu. Median Mean 3rd Qu. Max.
25.13 25.36 25.66 25.58 25.83 25.94
This behaviour of `runif` goes away when we use `kind
"Knuth-TAOCP-2002"`, and we get values that appear to be much more
evenly
spread out.
random_values = sapply(seeds, function(x) {
set.seed(x, kind = "Knuth-TAOCP-2002")
y = runif(1, 17, 26)
return(y)
})
*Output omitted.*
---
**The most interesting thing here is that this does not happen on Windows
-- only happens on Ubuntu** (`sessionInfo` output for Ubuntu & Windows
below).
# Windows output: #
> seeds = c(
+ "86548915", "86551615", "86566163",
"86577411", "86584144",
+ "86584272", "86620568", "86724613",
"86756002", "86768593",
"86772411",
+ "86781516", "86794389", "86805854",
"86814600", "86835092",
"86874179",
+ "86876466", "86901193", "86987847",
"86988080")
>
> random_values = sapply(seeds, function(x) {
+ set.seed(x)
+ y = runif(1, 17, 26)
+ return(y)
+ })
>
> summary(random_values)
Min. 1st Qu. Median Mean 3rd Qu. Max.
17.32 20.14 23.00 22.17 24.07 25.90
Can someone help understand what is going on?
Ubuntu
------
R version 3.4.0 (2017-04-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.2 LTS
Matrix products: default
BLAS: /usr/lib/libblas/libblas.so.3.6.0
LAPACK: /usr/lib/lapack/liblapack.so.3.6.0
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=en_US.UTF-8
[9] LC_ADDRESS=en_US.UTF-8 LC_TELEPHONE=en_US.UTF-8
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=en_US.UTF-8
attached base packages:
[1] parallel stats graphics grDevices utils datasets
methods base
other attached packages:
[1] RMySQL_0.10.8 DBI_0.6-1
[3] jsonlite_1.4 tidyjson_0.2.2
[5] optiRum_0.37.3 lubridate_1.6.0
[7] httr_1.2.1 gdata_2.18.0
[9] XLConnect_0.2-12 XLConnectJars_0.2-12
[11] data.table_1.10.4 stringr_1.2.0
[13] readxl_1.0.0 xlsx_0.5.7
[15] xlsxjars_0.6.1 rJava_0.9-8
[17] sqldf_0.4-10 RSQLite_1.1-2
[19] gsubfn_0.6-6 proto_1.0.0
[21] dplyr_0.5.0 purrr_0.2.4
[23] readr_1.1.1 tidyr_0.6.3
[25] tibble_1.3.0 tidyverse_1.1.1
[27] rBayesianOptimization_1.1.0 xgboost_0.6-4
[29] MLmetrics_1.1.1 caret_6.0-76
[31] ROCR_1.0-7 gplots_3.0.1
[33] effects_3.1-2 pROC_1.10.0
[35] pscl_1.4.9 lattice_0.20-35
[37] MASS_7.3-47 ggplot2_2.2.1
loaded via a namespace (and not attached):
[1] splines_3.4.0 foreach_1.4.3 AUC_0.3.0
modelr_0.1.0
[5] gtools_3.5.0 assertthat_0.2.0 stats4_3.4.0
cellranger_1.1.0
[9] quantreg_5.33 chron_2.3-50 digest_0.6.10
rvest_0.3.2
[13] minqa_1.2.4 colorspace_1.3-2 Matrix_1.2-10
plyr_1.8.4
[17] psych_1.7.3.21 XML_3.98-1.7 broom_0.4.2
SparseM_1.77
[21] haven_1.0.0 scales_0.4.1 lme4_1.1-13
MatrixModels_0.4-1
[25] mgcv_1.8-17 car_2.1-5 nnet_7.3-12
lazyeval_0.2.0
[29] pbkrtest_0.4-7 mnormt_1.5-5 magrittr_1.5
memoise_1.0.0
[33] nlme_3.1-131 forcats_0.2.0 xml2_1.1.1
foreign_0.8-69
[37] tools_3.4.0 hms_0.3 munsell_0.4.3
compiler_3.4.0
[41] caTools_1.17.1 rlang_0.1.1 grid_3.4.0
nloptr_1.0.4
[45] iterators_1.0.8 bitops_1.0-6 tcltk_3.4.0
gtable_0.2.0
[49] ModelMetrics_1.1.0 codetools_0.2-15 reshape2_1.4.2 R6_2.2.0
[53] knitr_1.15.1 KernSmooth_2.23-15 stringi_1.1.5
Rcpp_0.12.11
Windows
-------
> sessionInfo()
R version 3.3.2 (2016-10-31)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200)
locale:
[1] LC_COLLATE=English_India.1252 LC_CTYPE=English_India.1252
LC_MONETARY=English_India.1252
[4] LC_NUMERIC=C LC_TIME=English_India.1252
attached base packages:
[1] graphics grDevices utils datasets grid stats
methods base
other attached packages:
[1] bindrcpp_0.2 h2o_3.14.0.3 ggrepel_0.6.5
eulerr_1.1.0 VennDiagram_1.6.17
[6] futile.logger_1.4.3 scales_0.4.1 FinCal_0.6.3
xml2_1.0.0 httr_1.3.0
[11] wesanderson_0.3.2 wordcloud_2.5 RColorBrewer_1.1-2
htmltools_0.3.6 urltools_1.6.0
[16] timevis_0.4 dtplyr_0.0.1 magrittr_1.5
shiny_1.0.5 RODBC_1.3-14
[21] zoo_1.8-0 sqldf_0.4-10 RSQLite_1.1-2
gsubfn_0.6-6 proto_1.0.0
[26] gdata_2.17.0 stringr_1.2.0 XLConnect_0.2-12
XLConnectJars_0.2-12 data.table_1.10.4
[31] xlsx_0.5.7 xlsxjars_0.6.1 rJava_0.9-8
readxl_0.1.1 googlesheets_0.2.1
[36] jsonlite_1.5 tidyjson_0.2.1 RMySQL_0.10.9
RPostgreSQL_0.4-1 DBI_0.5-1
[41] dplyr_0.7.2 purrr_0.2.3 readr_1.1.1
tidyr_0.7.0 tibble_1.3.3
[46] ggplot2_2.2.0 tidyverse_1.0.0 lubridate_1.6.0
loaded via a namespace (and not attached):
[1] gtools_3.5.0 assertthat_0.2.0 triebeard_0.3.0
cellranger_1.1.0 yaml_2.1.14
[6] slam_0.1-40 lattice_0.20-34 glue_1.1.1
chron_2.3-48 digest_0.6.12.1
[11] colorspace_1.3-1 httpuv_1.3.5 plyr_1.8.4
pkgconfig_2.0.1 xtable_1.8-2
[16] lazyeval_0.2.0 mime_0.5 memoise_1.0.0
tools_3.3.2 hms_0.3
[21] munsell_0.4.3 lambda.r_1.1.9 rlang_0.1.1
RCurl_1.95-4.8 labeling_0.3
[26] bitops_1.0-6 tcltk_3.3.2 gtable_0.2.0
reshape2_1.4.2 R6_2.2.0
[31] bindr_0.1 futile.options_1.0.0 stringi_1.1.2
Rcpp_0.12.12.1
[1]: http://stat.ethz.ch/R-manual/R-devel/library/stats/html/Uniform.html
[[alternative HTML version deleted]]
Martin Maechler
2017-Nov-03 09:39 UTC
[Rd] 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 appropriate: It seems you have not read the help page for set.seed as I expect it from posters to R-devel. Why would you use strings instead of integers if you *had* read it ? > We are facing a weird situation in our code when using R's > [`runif`][1] and setting seed with `set.seed` with the > `kind = NULL` option (which resolves, unless I am > mistaken, to `kind = "default"`; the default being > `"Mersenne-Twister"`). again this is not what the help page says; rather | The use of ?kind = NULL? or ?normal.kind = NULL? in ?RNGkind? or | ?set.seed? selects the currently-used generator (including that | used in the previous session if the workspace has been restored): | if no generator has been used it selects ?"default"?. but as you have > 90 (!!) packages in your sessionInfo() below, why should we (or you) know if some of the things you did before or (implicitly) during loading all these packages did not change the RNG kind ? > We set the seed using (8 digit) unique IDs generated by an > upstream system, before calling `runif`: > seeds = c( "86548915", "86551615", "86566163", > "86577411", "86584144", "86584272", "86620568", > "86724613", "86756002", "86768593", "86772411", > "86781516", "86794389", "86805854", "86814600", > "86835092", "86874179", "86876466", "86901193", > "86987847", "86988080") > random_values = sapply(seeds, function(x) { > set.seed(x) > y = runif(1, 17, 26) > return(y) > }) Why do you do that? 1) You should set the seed *once*, not multiple times in one simulation. 2) Assuming that your strings are correctly translated to integers and the same on all platforms, independent of locales (!) etc, you are again not following the simple instruction on the help page: ?set.seed? uses a single integer argument to set as many seeds as are required. It is intended as a simple way to get quite different seeds by specifying small integer arguments, and also as ..... ..... Note: ** small ** integer Why do you assume 86901193 to be a small integer ? > This gives values that are **extremely** bunched together. >> summary(random_values) > Min. 1st Qu. Median Mean 3rd Qu. Max. 25.13 > 25.36 25.66 25.58 25.83 25.94 > This behaviour of `runif` goes away when we use `kind > "Knuth-TAOCP-2002"`, and we get values that appear to be > much more evenly spread out. > random_values = sapply(seeds, function(x) { > set.seed(x, kind = "Knuth-TAOCP-2002") y = runif(1, 17, > 26) return(y) }) > *Output omitted.* > --- > **The most interesting thing here is that this does not > happen on Windows -- only happens on Ubuntu** > (`sessionInfo` output for Ubuntu & Windows below). > # Windows output: # >> seeds = c( > + "86548915", "86551615", "86566163", "86577411", > "86584144", + "86584272", "86620568", "86724613", > "86756002", "86768593", "86772411", + "86781516", > "86794389", "86805854", "86814600", "86835092", > "86874179", + "86876466", "86901193", "86987847", > "86988080") >> >> random_values = sapply(seeds, function(x) { > + set.seed(x) + y = runif(1, 17, 26) + return(y) + }) >> >> summary(random_values) > Min. 1st Qu. Median Mean 3rd Qu. Max. 17.32 > 20.14 23.00 22.17 24.07 25.90 > Can someone help understand what is going on? > Ubuntu > ------ > R version 3.4.0 (2017-04-21) > Platform: x86_64-pc-linux-gnu (64-bit) > Running under: Ubuntu 16.04.2 LTS You have not learned to get a current version of R. ===> You should not write to R-devel (sorry if this may sound harsh ..) Hint: We know that Ubuntu LTS -- by its virtue of LTS (Long Time Support) will not update R. But the Ubuntu/Debian pages on CRAN tell you how to ensure to automatically get current versions of R on your ubuntu-run computer (Namely by adding a CRAN mirror to your ubuntu sources) And then in your sessionInfo : .... 38 packages attached + 56 namespaces loaded !! .... and similar nonsense (tons of packages+namespaces) on Windows which uses an even more outdated version of R 3.3.2. ------------- Can you please learn to work with a minimal reproducible example MRE (well you are close in your R code, but not if you load 50 packages and do how-knows-what before running the example, you RNGkind() and many other things could have been changed ...) Since you run ubuntu, you know the shell and you could (after installing a current version of R) put your MRE in a small *.R script and do R CMD BATCH --vanilla MRE.R which will produce MRE.Rout with all input/output BTW: Even on Windoze you can do similarly, once you've found the location of 'Rcmd.exe': ......\Rcmd BATCH --vanilla MRE.R should work there as well and deliver MRE.Rout - - - - - After doing all this, your problem may still be just because you are using much too large integers for the 'seed' argument of set.seed() I really really strongly believe you should have used R-help instead of R-devel. Best, Martin Maechler
Lukas Stadler
2017-Nov-03 10:04 UTC
[Rd] Extreme bunching of random values from runif with Mersenne-Twister seed
If I interpret the original message as ?I think there?s something wrong with R's random number generator?: Your assumption is that going from the seed to the first random number is a good hash function, which it isn?t. E.g., with Mersenne Twister it?s a couple of multiplications, bit shifts, xors and ands, and the few bits that vary in your seed end up in the less significant bits of the result. Something like the ?digest? package might be what you want, it provides proper hash functions. - Lukas> On 3 Nov 2017, at 10:39, Martin Maechler <maechler at stat.math.ethz.ch> wrote: > >>>>>> Tirthankar Chakravarty <tirthankar.lists at gmail.com> >>>>>> on Fri, 3 Nov 2017 13:19:12 +0530 writes: > >> This is cross-posted from SO >> (https://urldefense.proofpoint.com/v2/url?u=https-3A__stackoverflow.com_q_47079702_1414455&d=DwIGaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=sySSOv_y4gUrdhItlSw7q2z3RRR8JsPrnS8RhIHA9W4&m=mDEuT7697Im9mtm3dqOQF3Abpcn1ZsA1E_sZE-PZIGg&s=qm177vnypIq1tc3Km5gwocAEmlwieB9pD5jkClG0I-U&e=), 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 appropriate: > > It seems you have not read the help page for > set.seed as I expect it from posters to R-devel. > Why would you use strings instead of integers if you *had* read it ? > >> We are facing a weird situation in our code when using R's >> [`runif`][1] and setting seed with `set.seed` with the >> `kind = NULL` option (which resolves, unless I am >> mistaken, to `kind = "default"`; the default being >> `"Mersenne-Twister"`). > > again this is not what the help page says; rather > > | The use of ?kind = NULL? or ?normal.kind = NULL? in ?RNGkind? or > | ?set.seed? selects the currently-used generator (including that > | used in the previous session if the workspace has been restored): > | if no generator has been used it selects ?"default"?. > > but as you have > 90 (!!) packages in your sessionInfo() below, > why should we (or you) know if some of the things you did > before or (implicitly) during loading all these packages did not > change the RNG kind ? > >> We set the seed using (8 digit) unique IDs generated by an >> upstream system, before calling `runif`: > >> seeds = c( "86548915", "86551615", "86566163", >> "86577411", "86584144", "86584272", "86620568", >> "86724613", "86756002", "86768593", "86772411", >> "86781516", "86794389", "86805854", "86814600", >> "86835092", "86874179", "86876466", "86901193", >> "86987847", "86988080") > >> random_values = sapply(seeds, function(x) { >> set.seed(x) >> y = runif(1, 17, 26) >> return(y) >> }) > > Why do you do that? > > 1) You should set the seed *once*, not multiple times in one simulation. > > 2) Assuming that your strings are correctly translated to integers > and the same on all platforms, independent of locales (!) etc, > you are again not following the simple instruction on the help page: > > ?set.seed? uses a single integer argument to set as many seeds as > are required. It is intended as a simple way to get quite > different seeds by specifying small integer arguments, and also as > ..... > ..... > > Note: ** small ** integer > Why do you assume 86901193 to be a small integer ? > >> This gives values that are **extremely** bunched together. > >>> summary(random_values) >> Min. 1st Qu. Median Mean 3rd Qu. Max. 25.13 >> 25.36 25.66 25.58 25.83 25.94 > >> This behaviour of `runif` goes away when we use `kind >> "Knuth-TAOCP-2002"`, and we get values that appear to be >> much more evenly spread out. > >> random_values = sapply(seeds, function(x) { >> set.seed(x, kind = "Knuth-TAOCP-2002") y = runif(1, 17, >> 26) return(y) }) > >> *Output omitted.* > >> --- > >> **The most interesting thing here is that this does not >> happen on Windows -- only happens on Ubuntu** >> (`sessionInfo` output for Ubuntu & Windows below). > >> # Windows output: # > >>> seeds = c( >> + "86548915", "86551615", "86566163", "86577411", >> "86584144", + "86584272", "86620568", "86724613", >> "86756002", "86768593", "86772411", + "86781516", >> "86794389", "86805854", "86814600", "86835092", >> "86874179", + "86876466", "86901193", "86987847", >> "86988080") >>> >>> random_values = sapply(seeds, function(x) { >> + set.seed(x) + y = runif(1, 17, 26) + return(y) + }) >>> >>> summary(random_values) >> Min. 1st Qu. Median Mean 3rd Qu. Max. 17.32 >> 20.14 23.00 22.17 24.07 25.90 > >> Can someone help understand what is going on? > >> Ubuntu >> ------ > >> R version 3.4.0 (2017-04-21) >> Platform: x86_64-pc-linux-gnu (64-bit) >> Running under: Ubuntu 16.04.2 LTS > > You have not learned to get a current version of R. > ===> You should not write to R-devel (sorry if this may sound harsh ..) > > Hint: > We know that Ubuntu LTS -- by its virtue of LTS (Long Time > Support) will not update R. > But the Ubuntu/Debian pages on CRAN tell you how to ensure to > automatically get current versions of R on your ubuntu-run computer > (Namely by adding a CRAN mirror to your ubuntu sources) > > And then in your sessionInfo : > > .... > 38 packages attached + 56 namespaces loaded !! > .... > > and similar nonsense (tons of packages+namespaces) > on Windows which uses an even more outdated version of > R 3.3.2. > > ------------- > > Can you please learn to work with a minimal reproducible example MRE > (well you are close in your R code, but not if you load 50 > packages and do how-knows-what before running the example, > you RNGkind() and many other things could have been changed ...) > > Since you run ubuntu, you know the shell and you could > (after installing a current version of R) put your MRE in a > small *.R script and do > > R CMD BATCH --vanilla MRE.R > > which will produce MRE.Rout with all input/output > > BTW: Even on Windoze you can do similarly, once you've found the > location of 'Rcmd.exe': > > ......\Rcmd BATCH --vanilla MRE.R > > should work there as well and deliver MRE.Rout > > - - - - - > After doing all this, your problem may still be just > because you are using much too large integers for the 'seed' > argument of set.seed() > > I really really strongly believe you should have used R-help > instead of R-devel. > > Best, > Martin Maechler > > ______________________________________________ > R-devel at r-project.org mailing list > https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwIGaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=sySSOv_y4gUrdhItlSw7q2z3RRR8JsPrnS8RhIHA9W4&m=mDEuT7697Im9mtm3dqOQF3Abpcn1ZsA1E_sZE-PZIGg&s=ua3fUgGQ4bG_ImAKJ-_AHRdtFz0xtqvoA--cKTvFI1Q&e=
Tirthankar Chakravarty
2017-Nov-03 13:24 UTC
[Rd] 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 & zero down on the core issue, since I continue to believe that this is an issue with either R's implementation or a bad interaction of the seeds supplied with the Mersenne-Twister algorithm itself. The latter would require a deeper understanding of the algorithm than I have at the moment. If we can rule out the former through this thread, then I will pursue the latter solution path. Responses inline below, but summarizing: 1. All examples now are run using "R CMD BATCH --vanilla" as you have suggested, to ensure that no other loaded packages or namespace changes have interfered with the behaviour of `set.seed`. 2. Converting the character vector to integer vector has no impact on the output. 3. Upgrading to the latest version of R has no impact on the output. 4. Multiplying the seed vector by 10L causes the behaviour to vanish, calling into question the large integer theory. On Fri, Nov 3, 2017 at 3:09 PM, Martin Maechler <maechler at stat.math.ethz.ch> wrote:> Why R-devel -- R-help would have been appropriate: >> It seems you have not read the help page for > set.seed as I expect it from posters to R-devel. > Why would you use strings instead of integers if you *had* read it ? >The manual (which we did read) says: seed a single value, interpreted as an integer, We were confident of R coercing characters to integers correctly. We tested, prior to making this posting that the behaviour remains intact if we change the `seeds` variable from a character vector to the "equivalent" integer vector by hand.> seeds = c(86548915L, 86551615L, 86566163L, 86577411L, 86584144L,86584272L, + 86620568L, 86724613L, 86756002L, 86768593L, 86772411L, 86781516L, + 86794389L, 86805854L, 86814600L, 86835092L, 86874179L, 86876466L, + 86901193L, 86987847L, 86988080L)> > random_values = sapply(seeds, function(x) {+ set.seed(x) + y = runif(1, 17, 26) + return(y) + })> > summary(random_values)Min. 1st Qu. Median Mean 3rd Qu. Max. 25.13 25.36 25.66 25.58 25.83 25.94> > We are facing a weird situation in our code when using R's > > [`runif`][1] and setting seed with `set.seed` with the > > `kind = NULL` option (which resolves, unless I am > > mistaken, to `kind = "default"`; the default being > > `"Mersenne-Twister"`). > > again this is not what the help page says; rather > > | The use of ?kind = NULL? or ?normal.kind = NULL? in ?RNGkind? or > | ?set.seed? selects the currently-used generator (including that > | used in the previous session if the workspace has been restored): > | if no generator has been used it selects ?"default"?. > > but as you have > 90 (!!) packages in your sessionInfo() below, > why should we (or you) know if some of the things you did > before or (implicitly) during loading all these packages did not > change the RNG kind ? >Agreed. We are running this system in production, and we will need `set.seed` to behave reliably with this session, however, as you say, we are claiming that there is an issue with the PRNG, so should isolate to an environment that does not have any of the attendant potential confounding factors that come with having 90 packages loaded (did you count?). As mentioned above, we have rerun all examples using "R CMD BATCH --vanilla" and we can report that the output is unchanged.> > > We set the seed using (8 digit) unique IDs generated by an > > upstream system, before calling `runif`: > > > seeds = c( "86548915", "86551615", "86566163", > > "86577411", "86584144", "86584272", "86620568", > > "86724613", "86756002", "86768593", "86772411", > > "86781516", "86794389", "86805854", "86814600", > > "86835092", "86874179", "86876466", "86901193", > > "86987847", "86988080") > > > random_values = sapply(seeds, function(x) { > > set.seed(x) > > y = runif(1, 17, 26) > > return(y) > > }) > > Why do you do that? > > 1) You should set the seed *once*, not multiple times in one simulation. >This code is written like this since this seed is set every time the function (API) is called for call-level replicability. It doesn't make a lot of sense in an MRE, but this is a critical component of the larger function. We do acknowledge that for any one of the seeds in the vector `seeds` the vector of draws appears to have the uniform distribution.> 2) Assuming that your strings are correctly translated to integers > and the same on all platforms, independent of locales (!) etc, > you are again not following the simple instruction on the help page: > > ?set.seed? uses a single integer argument to set as many seeds as > are required. It is intended as a simple way to get quite > different seeds by specifying small integer arguments, and also as > ..... > ..... > > Note: ** small ** integer > Why do you assume 86901193 to be a small integer ? >Because 86901193/2^32 = 0.02. What is a "small integer"?> > > This gives values that are **extremely** bunched together. > > >> summary(random_values) > > Min. 1st Qu. Median Mean 3rd Qu. Max. 25.13 > > 25.36 25.66 25.58 25.83 25.94 > > > This behaviour of `runif` goes away when we use `kind > > "Knuth-TAOCP-2002"`, and we get values that appear to be > > much more evenly spread out. > > > random_values = sapply(seeds, function(x) { > > set.seed(x, kind = "Knuth-TAOCP-2002") y = runif(1, 17, > > 26) return(y) }) > > > *Output omitted.* > > > --- > > > **The most interesting thing here is that this does not > > happen on Windows -- only happens on Ubuntu** > > (`sessionInfo` output for Ubuntu & Windows below). > > > # Windows output: # > > >> seeds = c( > > + "86548915", "86551615", "86566163", "86577411", > > "86584144", + "86584272", "86620568", "86724613", > > "86756002", "86768593", "86772411", + "86781516", > > "86794389", "86805854", "86814600", "86835092", > > "86874179", + "86876466", "86901193", "86987847", > > "86988080") > >> > >> random_values = sapply(seeds, function(x) { > > + set.seed(x) + y = runif(1, 17, 26) + return(y) + }) > >> > >> summary(random_values) > > Min. 1st Qu. Median Mean 3rd Qu. Max. 17.32 > > 20.14 23.00 22.17 24.07 25.90 > > > Can someone help understand what is going on? > > > Ubuntu > > ------ > > > R version 3.4.0 (2017-04-21) > > Platform: x86_64-pc-linux-gnu (64-bit) > > Running under: Ubuntu 16.04.2 LTS > > You have not learned to get a current version of R. > ===> You should not write to R-devel (sorry if this may sound harsh ..) >We do spend a while on certain versions of R since upgrading our systems in production is not something we are able to do frequently & this version is only 6 months old. However, addressing your concern, upgrading to R 3.4.2 leaves the output unchanged.> - - - - - > After doing all this, your problem may still be just > because you are using much too large integers for the 'seed' > argument of set.seed() >Note that multiplying the reported set of seeds by 10, results in expected output, so not clear if there is a sweet spot that bugs out the Mersenne-Twister algorithm: seeds = c(86548915L, 86551615L, 86566163L, 86577411L, 86584144L, 86584272L, 86620568L, 86724613L, 86756002L, 86768593L, 86772411L, 86781516L, 86794389L, 86805854L, 86814600L, 86835092L, 86874179L, 86876466L, 86901193L, 86987847L, 86988080L)*10 random_values = sapply(seeds, function(x) { set.seed(x) y = runif(1, 17, 26) return(y) }) summary(random_values)> I really really strongly believe you should have used R-help > instead of R-devel. > > Best, > Martin Maechler >If you continue to believe with the inputs given in this reply that this should be on R-help, we will switch over. Your continued help would be appreciated in understanding the issue. T [[alternative HTML version deleted]]
William Dunlap
2017-Nov-03 16:28 UTC
[Rd] 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 come up with seeds that give about the same first value:> Filter(function(s){set.seed(s);runif(1,17,26)>25.99}, 1:10000)[1] 514 532 1951 2631 3974 4068 4229 6092 6432 7264 9090 Bill Dunlap TIBCO Software wdunlap tibco.com On Fri, Nov 3, 2017 at 12:49 AM, Tirthankar Chakravarty < tirthankar.lists at gmail.com> wrote:> 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. > > We are facing a weird situation in our code when using R's [`runif`][1] and > setting seed with `set.seed` with the `kind = NULL` option (which resolves, > unless I am mistaken, to `kind = "default"`; the default being > `"Mersenne-Twister"`). > > We set the seed using (8 digit) unique IDs generated by an upstream system, > before calling `runif`: > > seeds = c( > "86548915", "86551615", "86566163", "86577411", "86584144", > "86584272", "86620568", "86724613", "86756002", "86768593", > "86772411", > "86781516", "86794389", "86805854", "86814600", "86835092", > "86874179", > "86876466", "86901193", "86987847", "86988080") > > random_values = sapply(seeds, function(x) { > set.seed(x) > y = runif(1, 17, 26) > return(y) > }) > > This gives values that are **extremely** bunched together. > > > summary(random_values) > Min. 1st Qu. Median Mean 3rd Qu. Max. > 25.13 25.36 25.66 25.58 25.83 25.94 > > This behaviour of `runif` goes away when we use `kind > "Knuth-TAOCP-2002"`, and we get values that appear to be much more evenly > spread out. > > random_values = sapply(seeds, function(x) { > set.seed(x, kind = "Knuth-TAOCP-2002") > y = runif(1, 17, 26) > return(y) > }) > > *Output omitted.* > > --- > > **The most interesting thing here is that this does not happen on Windows > -- only happens on Ubuntu** (`sessionInfo` output for Ubuntu & Windows > below). > > # Windows output: # > > > seeds = c( > + "86548915", "86551615", "86566163", "86577411", "86584144", > + "86584272", "86620568", "86724613", "86756002", "86768593", > "86772411", > + "86781516", "86794389", "86805854", "86814600", "86835092", > "86874179", > + "86876466", "86901193", "86987847", "86988080") > > > > random_values = sapply(seeds, function(x) { > + set.seed(x) > + y = runif(1, 17, 26) > + return(y) > + }) > > > > summary(random_values) > Min. 1st Qu. Median Mean 3rd Qu. Max. > 17.32 20.14 23.00 22.17 24.07 25.90 > > Can someone help understand what is going on? > > Ubuntu > ------ > > R version 3.4.0 (2017-04-21) > Platform: x86_64-pc-linux-gnu (64-bit) > Running under: Ubuntu 16.04.2 LTS > > Matrix products: default > BLAS: /usr/lib/libblas/libblas.so.3.6.0 > LAPACK: /usr/lib/lapack/liblapack.so.3.6.0 > > locale: > [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C > [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 > [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 > [7] LC_PAPER=en_US.UTF-8 LC_NAME=en_US.UTF-8 > [9] LC_ADDRESS=en_US.UTF-8 LC_TELEPHONE=en_US.UTF-8 > [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=en_US.UTF-8 > > attached base packages: > [1] parallel stats graphics grDevices utils datasets > methods base > > other attached packages: > [1] RMySQL_0.10.8 DBI_0.6-1 > [3] jsonlite_1.4 tidyjson_0.2.2 > [5] optiRum_0.37.3 lubridate_1.6.0 > [7] httr_1.2.1 gdata_2.18.0 > [9] XLConnect_0.2-12 XLConnectJars_0.2-12 > [11] data.table_1.10.4 stringr_1.2.0 > [13] readxl_1.0.0 xlsx_0.5.7 > [15] xlsxjars_0.6.1 rJava_0.9-8 > [17] sqldf_0.4-10 RSQLite_1.1-2 > [19] gsubfn_0.6-6 proto_1.0.0 > [21] dplyr_0.5.0 purrr_0.2.4 > [23] readr_1.1.1 tidyr_0.6.3 > [25] tibble_1.3.0 tidyverse_1.1.1 > [27] rBayesianOptimization_1.1.0 xgboost_0.6-4 > [29] MLmetrics_1.1.1 caret_6.0-76 > [31] ROCR_1.0-7 gplots_3.0.1 > [33] effects_3.1-2 pROC_1.10.0 > [35] pscl_1.4.9 lattice_0.20-35 > [37] MASS_7.3-47 ggplot2_2.2.1 > > loaded via a namespace (and not attached): > [1] splines_3.4.0 foreach_1.4.3 AUC_0.3.0 > modelr_0.1.0 > [5] gtools_3.5.0 assertthat_0.2.0 stats4_3.4.0 > cellranger_1.1.0 > [9] quantreg_5.33 chron_2.3-50 digest_0.6.10 > rvest_0.3.2 > [13] minqa_1.2.4 colorspace_1.3-2 Matrix_1.2-10 > plyr_1.8.4 > [17] psych_1.7.3.21 XML_3.98-1.7 broom_0.4.2 > SparseM_1.77 > [21] haven_1.0.0 scales_0.4.1 lme4_1.1-13 > MatrixModels_0.4-1 > [25] mgcv_1.8-17 car_2.1-5 nnet_7.3-12 > lazyeval_0.2.0 > [29] pbkrtest_0.4-7 mnormt_1.5-5 magrittr_1.5 > memoise_1.0.0 > [33] nlme_3.1-131 forcats_0.2.0 xml2_1.1.1 > foreign_0.8-69 > [37] tools_3.4.0 hms_0.3 munsell_0.4.3 > compiler_3.4.0 > [41] caTools_1.17.1 rlang_0.1.1 grid_3.4.0 > nloptr_1.0.4 > [45] iterators_1.0.8 bitops_1.0-6 tcltk_3.4.0 > gtable_0.2.0 > [49] ModelMetrics_1.1.0 codetools_0.2-15 reshape2_1.4.2 R6_2.2.0 > > [53] knitr_1.15.1 KernSmooth_2.23-15 stringi_1.1.5 > Rcpp_0.12.11 > > > > Windows > ------- > > > sessionInfo() > R version 3.3.2 (2016-10-31) > Platform: x86_64-w64-mingw32/x64 (64-bit) > Running under: Windows >= 8 x64 (build 9200) > > locale: > [1] LC_COLLATE=English_India.1252 LC_CTYPE=English_India.1252 > LC_MONETARY=English_India.1252 > [4] LC_NUMERIC=C LC_TIME=English_India.1252 > > attached base packages: > [1] graphics grDevices utils datasets grid stats > methods base > > other attached packages: > [1] bindrcpp_0.2 h2o_3.14.0.3 ggrepel_0.6.5 > eulerr_1.1.0 VennDiagram_1.6.17 > [6] futile.logger_1.4.3 scales_0.4.1 FinCal_0.6.3 > xml2_1.0.0 httr_1.3.0 > [11] wesanderson_0.3.2 wordcloud_2.5 RColorBrewer_1.1-2 > htmltools_0.3.6 urltools_1.6.0 > [16] timevis_0.4 dtplyr_0.0.1 magrittr_1.5 > shiny_1.0.5 RODBC_1.3-14 > [21] zoo_1.8-0 sqldf_0.4-10 RSQLite_1.1-2 > gsubfn_0.6-6 proto_1.0.0 > [26] gdata_2.17.0 stringr_1.2.0 XLConnect_0.2-12 > XLConnectJars_0.2-12 data.table_1.10.4 > [31] xlsx_0.5.7 xlsxjars_0.6.1 rJava_0.9-8 > readxl_0.1.1 googlesheets_0.2.1 > [36] jsonlite_1.5 tidyjson_0.2.1 RMySQL_0.10.9 > RPostgreSQL_0.4-1 DBI_0.5-1 > [41] dplyr_0.7.2 purrr_0.2.3 readr_1.1.1 > tidyr_0.7.0 tibble_1.3.3 > [46] ggplot2_2.2.0 tidyverse_1.0.0 lubridate_1.6.0 > > loaded via a namespace (and not attached): > [1] gtools_3.5.0 assertthat_0.2.0 triebeard_0.3.0 > cellranger_1.1.0 yaml_2.1.14 > [6] slam_0.1-40 lattice_0.20-34 glue_1.1.1 > chron_2.3-48 digest_0.6.12.1 > [11] colorspace_1.3-1 httpuv_1.3.5 plyr_1.8.4 > pkgconfig_2.0.1 xtable_1.8-2 > [16] lazyeval_0.2.0 mime_0.5 memoise_1.0.0 > tools_3.3.2 hms_0.3 > [21] munsell_0.4.3 lambda.r_1.1.9 rlang_0.1.1 > RCurl_1.95-4.8 labeling_0.3 > [26] bitops_1.0-6 tcltk_3.3.2 gtable_0.2.0 > reshape2_1.4.2 R6_2.2.0 > [31] bindr_0.1 futile.options_1.0.0 stringi_1.1.2 > Rcpp_0.12.12.1 > > [1]: http://stat.ethz.ch/R-manual/R-devel/library/stats/html/ > Uniform.html > > [[alternative HTML version deleted]] > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >[[alternative HTML version deleted]]
Tirthankar Chakravarty
2017-Nov-03 17:31 UTC
[Rd] 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 edge case. Would be good to know what seeds will and will not work, and why." These numbers are generated by an application that serves a form, and associates form IDs in a sequence. The application calls our API depending on the form values entered by users, which in turn calls our R code that executes some code that needs an RNG. Since the API has to be stateless, to be able to replicate the results for possible debugging, we need to draw random numbers in a way that we can replicate the results of the API response -- we use the form ID as seeds. I repeat, there is no design or anything adversarial about the way that these numbers were generated -- the system generating these numbers and the users entering inputs have no conception of our use of an RNG -- this is meant to just be a random sequence of form IDs. This issue was discovered completely by chance when the output of the API was observed to be highly non-random. It is possible that it is a 1/10^8 chance, but that is hard to believe, given that the API hit depends on user input. Note also that the issue goes away when we use a different RNG as mentioned below. T On Fri, Nov 3, 2017 at 9:58 PM, William Dunlap <wdunlap at tibco.com> wrote:> 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 come up > with seeds that give about the same first value: > > > Filter(function(s){set.seed(s);runif(1,17,26)>25.99}, 1:10000) > [1] 514 532 1951 2631 3974 4068 4229 6092 6432 7264 9090 > > > > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > On Fri, Nov 3, 2017 at 12:49 AM, Tirthankar Chakravarty < > tirthankar.lists at gmail.com> wrote: > >> This is cross-posted from SO (https://stackoverflow.com/q/4 >> 7079702/1414455), >> but I now feel that this needs someone from R-Devel to help understand why >> this is happening. >> >> We are facing a weird situation in our code when using R's [`runif`][1] >> and >> setting seed with `set.seed` with the `kind = NULL` option (which >> resolves, >> unless I am mistaken, to `kind = "default"`; the default being >> `"Mersenne-Twister"`). >> >> We set the seed using (8 digit) unique IDs generated by an upstream >> system, >> before calling `runif`: >> >> seeds = c( >> "86548915", "86551615", "86566163", "86577411", "86584144", >> "86584272", "86620568", "86724613", "86756002", "86768593", >> "86772411", >> "86781516", "86794389", "86805854", "86814600", "86835092", >> "86874179", >> "86876466", "86901193", "86987847", "86988080") >> >> random_values = sapply(seeds, function(x) { >> set.seed(x) >> y = runif(1, 17, 26) >> return(y) >> }) >> >> This gives values that are **extremely** bunched together. >> >> > summary(random_values) >> Min. 1st Qu. Median Mean 3rd Qu. Max. >> 25.13 25.36 25.66 25.58 25.83 25.94 >> >> This behaviour of `runif` goes away when we use `kind >> "Knuth-TAOCP-2002"`, and we get values that appear to be much more evenly >> spread out. >> >> random_values = sapply(seeds, function(x) { >> set.seed(x, kind = "Knuth-TAOCP-2002") >> y = runif(1, 17, 26) >> return(y) >> }) >> >> *Output omitted.* >> >> --- >> >> **The most interesting thing here is that this does not happen on Windows >> -- only happens on Ubuntu** (`sessionInfo` output for Ubuntu & Windows >> below). >> >> # Windows output: # >> >> > seeds = c( >> + "86548915", "86551615", "86566163", "86577411", "86584144", >> + "86584272", "86620568", "86724613", "86756002", "86768593", >> "86772411", >> + "86781516", "86794389", "86805854", "86814600", "86835092", >> "86874179", >> + "86876466", "86901193", "86987847", "86988080") >> > >> > random_values = sapply(seeds, function(x) { >> + set.seed(x) >> + y = runif(1, 17, 26) >> + return(y) >> + }) >> > >> > summary(random_values) >> Min. 1st Qu. Median Mean 3rd Qu. Max. >> 17.32 20.14 23.00 22.17 24.07 25.90 >> >> Can someone help understand what is going on? >> >> Ubuntu >> ------ >> >> R version 3.4.0 (2017-04-21) >> Platform: x86_64-pc-linux-gnu (64-bit) >> Running under: Ubuntu 16.04.2 LTS >> >> Matrix products: default >> BLAS: /usr/lib/libblas/libblas.so.3.6.0 >> LAPACK: /usr/lib/lapack/liblapack.so.3.6.0 >> >> locale: >> [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C >> [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 >> [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 >> [7] LC_PAPER=en_US.UTF-8 LC_NAME=en_US.UTF-8 >> [9] LC_ADDRESS=en_US.UTF-8 LC_TELEPHONE=en_US.UTF-8 >> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=en_US.UTF-8 >> >> attached base packages: >> [1] parallel stats graphics grDevices utils datasets >> methods base >> >> other attached packages: >> [1] RMySQL_0.10.8 DBI_0.6-1 >> [3] jsonlite_1.4 tidyjson_0.2.2 >> [5] optiRum_0.37.3 lubridate_1.6.0 >> [7] httr_1.2.1 gdata_2.18.0 >> [9] XLConnect_0.2-12 XLConnectJars_0.2-12 >> [11] data.table_1.10.4 stringr_1.2.0 >> [13] readxl_1.0.0 xlsx_0.5.7 >> [15] xlsxjars_0.6.1 rJava_0.9-8 >> [17] sqldf_0.4-10 RSQLite_1.1-2 >> [19] gsubfn_0.6-6 proto_1.0.0 >> [21] dplyr_0.5.0 purrr_0.2.4 >> [23] readr_1.1.1 tidyr_0.6.3 >> [25] tibble_1.3.0 tidyverse_1.1.1 >> [27] rBayesianOptimization_1.1.0 xgboost_0.6-4 >> [29] MLmetrics_1.1.1 caret_6.0-76 >> [31] ROCR_1.0-7 gplots_3.0.1 >> [33] effects_3.1-2 pROC_1.10.0 >> [35] pscl_1.4.9 lattice_0.20-35 >> [37] MASS_7.3-47 ggplot2_2.2.1 >> >> loaded via a namespace (and not attached): >> [1] splines_3.4.0 foreach_1.4.3 AUC_0.3.0 >> modelr_0.1.0 >> [5] gtools_3.5.0 assertthat_0.2.0 stats4_3.4.0 >> cellranger_1.1.0 >> [9] quantreg_5.33 chron_2.3-50 digest_0.6.10 >> rvest_0.3.2 >> [13] minqa_1.2.4 colorspace_1.3-2 Matrix_1.2-10 >> plyr_1.8.4 >> [17] psych_1.7.3.21 XML_3.98-1.7 broom_0.4.2 >> SparseM_1.77 >> [21] haven_1.0.0 scales_0.4.1 lme4_1.1-13 >> MatrixModels_0.4-1 >> [25] mgcv_1.8-17 car_2.1-5 nnet_7.3-12 >> lazyeval_0.2.0 >> [29] pbkrtest_0.4-7 mnormt_1.5-5 magrittr_1.5 >> memoise_1.0.0 >> [33] nlme_3.1-131 forcats_0.2.0 xml2_1.1.1 >> foreign_0.8-69 >> [37] tools_3.4.0 hms_0.3 munsell_0.4.3 >> compiler_3.4.0 >> [41] caTools_1.17.1 rlang_0.1.1 grid_3.4.0 >> nloptr_1.0.4 >> [45] iterators_1.0.8 bitops_1.0-6 tcltk_3.4.0 >> gtable_0.2.0 >> [49] ModelMetrics_1.1.0 codetools_0.2-15 reshape2_1.4.2 R6_2.2.0 >> >> [53] knitr_1.15.1 KernSmooth_2.23-15 stringi_1.1.5 >> Rcpp_0.12.11 >> >> >> >> Windows >> ------- >> >> > sessionInfo() >> R version 3.3.2 (2016-10-31) >> Platform: x86_64-w64-mingw32/x64 (64-bit) >> Running under: Windows >= 8 x64 (build 9200) >> >> locale: >> [1] LC_COLLATE=English_India.1252 LC_CTYPE=English_India.1252 >> LC_MONETARY=English_India.1252 >> [4] LC_NUMERIC=C LC_TIME=English_India.1252 >> >> attached base packages: >> [1] graphics grDevices utils datasets grid stats >> methods base >> >> other attached packages: >> [1] bindrcpp_0.2 h2o_3.14.0.3 ggrepel_0.6.5 >> eulerr_1.1.0 VennDiagram_1.6.17 >> [6] futile.logger_1.4.3 scales_0.4.1 FinCal_0.6.3 >> xml2_1.0.0 httr_1.3.0 >> [11] wesanderson_0.3.2 wordcloud_2.5 RColorBrewer_1.1-2 >> htmltools_0.3.6 urltools_1.6.0 >> [16] timevis_0.4 dtplyr_0.0.1 magrittr_1.5 >> shiny_1.0.5 RODBC_1.3-14 >> [21] zoo_1.8-0 sqldf_0.4-10 RSQLite_1.1-2 >> gsubfn_0.6-6 proto_1.0.0 >> [26] gdata_2.17.0 stringr_1.2.0 XLConnect_0.2-12 >> XLConnectJars_0.2-12 data.table_1.10.4 >> [31] xlsx_0.5.7 xlsxjars_0.6.1 rJava_0.9-8 >> readxl_0.1.1 googlesheets_0.2.1 >> [36] jsonlite_1.5 tidyjson_0.2.1 RMySQL_0.10.9 >> RPostgreSQL_0.4-1 DBI_0.5-1 >> [41] dplyr_0.7.2 purrr_0.2.3 readr_1.1.1 >> tidyr_0.7.0 tibble_1.3.3 >> [46] ggplot2_2.2.0 tidyverse_1.0.0 lubridate_1.6.0 >> >> loaded via a namespace (and not attached): >> [1] gtools_3.5.0 assertthat_0.2.0 triebeard_0.3.0 >> cellranger_1.1.0 yaml_2.1.14 >> [6] slam_0.1-40 lattice_0.20-34 glue_1.1.1 >> chron_2.3-48 digest_0.6.12.1 >> [11] colorspace_1.3-1 httpuv_1.3.5 plyr_1.8.4 >> pkgconfig_2.0.1 xtable_1.8-2 >> [16] lazyeval_0.2.0 mime_0.5 memoise_1.0.0 >> tools_3.3.2 hms_0.3 >> [21] munsell_0.4.3 lambda.r_1.1.9 rlang_0.1.1 >> RCurl_1.95-4.8 labeling_0.3 >> [26] bitops_1.0-6 tcltk_3.3.2 gtable_0.2.0 >> reshape2_1.4.2 R6_2.2.0 >> [31] bindr_0.1 futile.options_1.0.0 stringi_1.1.2 >> Rcpp_0.12.12.1 >> >> [1]: http://stat.ethz.ch/R-manual/R-devel/library/stats/html/Unif >> orm.html >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-devel at r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel >> > >[[alternative HTML version deleted]]
Possibly Parallel Threads
- Extreme bunching of random values from runif with Mersenne-Twister seed
- Extreme bunching of random values from runif with Mersenne-Twister seed
- Extreme bunching of random values from runif with Mersenne-Twister seed
- Extreme bunching of random values from runif with Mersenne-Twister seed
- Extreme bunching of random values from runif with Mersenne-Twister seed