[R] How many random numbers needed?
Hello R-People! I am running R 2.7.0 on a Power Book (Tiger). (I am still R and statistics beginner) Perhaps this is another stupid question of me, but I was wondering how I know the needed random (set.seed) numbers, when running randomForest (library randomForest) on a large dataset. Thanks in advance Birgit Birgit Lemcke Institut für Systematische Botanik Zollikerstrasse 107 CH-8008 Zürich Switzerland Ph: +41 (0)44 634 8351 [EMAIL PROTECTED] 175 Jahre UZH «staunen.erleben.begreifen. Naturwissenschaft zum Anfassen.» MNF-Jubiläumsevent für gross und klein. 19. April 2008, 10.00 Uhr bis 02.00 Uhr Campus Irchel, Winterthurerstrasse 190, 8057 Zürich Weitere Informationen http://www.175jahre.uzh.ch/naturwissenschaft __ R-help@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.
Re: [R] How many random numbers needed?
On Sat, 2008-05-10 at 13:21 +0200, Birgit Lemcke wrote: Hello R-People! I am running R 2.7.0 on a Power Book (Tiger). (I am still R and statistics beginner) Perhaps this is another stupid question of me, but I was wondering how I know the needed random (set.seed) numbers, when running randomForest (library randomForest) on a large dataset. The seed is just a starting point for the RNG. You can draw as many numbers as you like once the RNG has been seeded. The ability to set the seed allows repeated runs of functions like randomForest to provide the same results for each run. This is a basic requirement of reproducible research. require(randomForest) set.seed(1) mod1 - randomForest(Species ~ ., data = iris) mod2 - randomForest(Species ~ ., data = iris) set.seed(1) mod3 - randomForest(Species ~ ., data = iris) all.equal(mod1, mod2) all.equal(mod1, mod3) You could put whatever (within reason - up to limits of an integer in R) into the set.seed function, but the point is to provide the same number in the seed if you want to make sure your results are reproducible. HTH G Thanks in advance Birgit Birgit Lemcke Institut für Systematische Botanik Zollikerstrasse 107 CH-8008 Zürich Switzerland Ph: +41 (0)44 634 8351 [EMAIL PROTECTED] 175 Jahre UZH «staunen.erleben.begreifen. Naturwissenschaft zum Anfassen.» MNF-Jubiläumsevent für gross und klein. 19. April 2008, 10.00 Uhr bis 02.00 Uhr Campus Irchel, Winterthurerstrasse 190, 8057 Zürich Weitere Informationen http://www.175jahre.uzh.ch/naturwissenschaft __ R-help@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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% __ R-help@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.
Re: [R] How many random numbers needed?
Thank you Gavin. I knew about the meaning set.seed for reproducability but I did not realise that it is only the starting point. Is it possible that very small or very big random numbers cause any kind of bias? B. Am 10.05.2008 um 14:50 schrieb Gavin Simpson: On Sat, 2008-05-10 at 13:21 +0200, Birgit Lemcke wrote: Hello R-People! I am running R 2.7.0 on a Power Book (Tiger). (I am still R and statistics beginner) Perhaps this is another stupid question of me, but I was wondering how I know the needed random (set.seed) numbers, when running randomForest (library randomForest) on a large dataset. The seed is just a starting point for the RNG. You can draw as many numbers as you like once the RNG has been seeded. The ability to set the seed allows repeated runs of functions like randomForest to provide the same results for each run. This is a basic requirement of reproducible research. require(randomForest) set.seed(1) mod1 - randomForest(Species ~ ., data = iris) mod2 - randomForest(Species ~ ., data = iris) set.seed(1) mod3 - randomForest(Species ~ ., data = iris) all.equal(mod1, mod2) all.equal(mod1, mod3) You could put whatever (within reason - up to limits of an integer in R) into the set.seed function, but the point is to provide the same number in the seed if you want to make sure your results are reproducible. HTH G Thanks in advance Birgit Birgit Lemcke Institut für Systematische Botanik Zollikerstrasse 107 CH-8008 Zürich Switzerland Ph: +41 (0)44 634 8351 [EMAIL PROTECTED] 175 Jahre UZH «staunen.erleben.begreifen. Naturwissenschaft zum Anfassen.» MNF-Jubiläumsevent für gross und klein. 19. April 2008, 10.00 Uhr bis 02.00 Uhr Campus Irchel, Winterthurerstrasse 190, 8057 Zürich Weitere Informationen http://www.175jahre.uzh.ch/naturwissenschaft __ R-help@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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Birgit Lemcke Institut für Systematische Botanik Zollikerstrasse 107 CH-8008 Zürich Switzerland Ph: +41 (0)44 634 8351 [EMAIL PROTECTED] 175 Jahre UZH «staunen.erleben.begreifen. Naturwissenschaft zum Anfassen.» MNF-Jubiläumsevent für gross und klein. 19. April 2008, 10.00 Uhr bis 02.00 Uhr Campus Irchel, Winterthurerstrasse 190, 8057 Zürich Weitere Informationen http://www.175jahre.uzh.ch/naturwissenschaft __ R-help@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.
