[R] set.seed and for loop

[jim holtman]

If you feel the need to go back and recreate a random series, then
same the seed (.Random.seed) and restore it:

> set.seed(1001)
> total <- 0
> data <- vector("list", 30)
> seeds <- vector("list", 30)
> for(i in 1:30) {
+  seeds[[i]] <- .Random.seed
+  data[[i]] <- runif(50)
+ }
>
> .Random.seed <- seeds[[23]]  # restore
> data.23 <- runif(50)
> data.23
 [1] 0.684727876 0.592993730 0.879359238 0.454304600 0.754685981
0.119436749 0.527867847 0.265443455
 [9] 0.887112712 0.043309227 0.001381898 0.403483404 0.042224167
0.698174037 0.334604909 0.059465646
[17] 0.374227434 0.014508142 0.265783354 0.023154917 0.668829829
0.184914632 0.479524914 0.644859846
[25] 0.497644242 0.569325789 0.257636746 0.720526541 0.541526487
0.904469943 0.755720327 0.729912488
[33] 0.388004197 0.940454649 0.545474130 0.285013104 0.379244716
0.012338111 0.192581106 0.535863633
[41] 0.496777643 0.323488796 0.414391018 0.971135722 0.763092648
0.120187724 0.402572384 0.081896175
[49] 0.303378141 0.002711767
> data[[23]]
 [1] 0.684727876 0.592993730 0.879359238 0.454304600 0.754685981
0.119436749 0.527867847 0.265443455
 [9] 0.887112712 0.043309227 0.001381898 0.403483404 0.042224167
0.698174037 0.334604909 0.059465646
[17] 0.374227434 0.014508142 0.265783354 0.023154917 0.668829829
0.184914632 0.479524914 0.644859846
[25] 0.497644242 0.569325789 0.257636746 0.720526541 0.541526487
0.904469943 0.755720327 0.729912488
[33] 0.388004197 0.940454649 0.545474130 0.285013104 0.379244716
0.012338111 0.192581106 0.535863633
[41] 0.496777643 0.323488796 0.414391018 0.971135722 0.763092648
0.120187724 0.402572384 0.081896175
[49] 0.303378141 0.002711767
>


On Thu, Jun 9, 2011 at 11:23 AM, Samuel Le <Samuel.Le at srlglobal.com> wrote:
> What about:
> set.seed(1001)
> total <- 0
> data <- vector("list", 30)
> for(i in 1:30) {
>  data[[i]] <- runif(50)
> }
> set.seed(1001)
> data[[23]] <- runif(50)
>
> HTH
> Samuel
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Soyeon Kim
> Sent: 09 June 2011 16:15
> To: r-help
> Subject: [R] set.seed and for loop
>
> Dear All,
>
> This is hard to describe so I made a simple example.
> set.seed(1001)
> total <- 0
> data <- vector("list", 30)
> for(i in 1:30) {
>  data[[i]] <- runif(50)
> }
> Let's call a data set runif(50).
> While the for loop is running, 100 data sets  are generated.
> I want to restore 23th data set (the data set generated in 23th for
> loop) without the loop.
> I've tried set.seed(1023) runif(50)
> but this is different data from the data set gotten from 23th for loop.
> How can I get 23th data set without the loop?
>
> Thank you,
> Soyeon
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>
>
> __________ Information from ESET NOD32 Antivirus, version of virus signature database 6193 (20110609) __________
>
> The message was checked by ESET NOD32 Antivirus.
>
> http://www.eset.com
>
>
>
> __________ Information from ESET NOD32 Antivirus, version of virus signature database 6193 (20110609) __________
>
> The message was checked by ESET NOD32 Antivirus.
>
> http://www.eset.com
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>



-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?