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
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-
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and provide commented, minimal, self-contained, reproducible code.
--
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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/
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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.
