Assignment to a list in a function does not behave as I would expect.
The following function illustrates the point
#----------------------------------------
temp _ function()
{
nf _ 2
ns _ 5
z _ vector("list",ns)
x _ matrix(NA,nrow=ns,ncol=nf)
for(j in 1:ns)
{
for(i in 1:nf)
{
x[,i] _ i+j*100
}
z[[j]] _ x
print(z[[j]])
}
z
}
#------------------------------------------
Replacing the line that assigns z[[j]] with the following 2 lines produces
the expected result
y _ x
z[[j]] _ y
Furthermore, I get the expected result by running the function under Splus
6.
My question is: do we have an instance of assignment by reference here? Is
this behaviour intended?
Giles Heywood
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"Heywood, Giles" <giles.heywood at CommerzbankIB.com> writes:> Assignment to a list in a function does not behave as I would expect. > > The following function illustrates the point > > #---------------------------------------- > temp _ function() > { > nf _ 2 > ns _ 5 > z _ vector("list",ns) > x _ matrix(NA,nrow=ns,ncol=nf) > for(j in 1:ns) > { > for(i in 1:nf) > { > x[,i] _ i+j*100 > } > > z[[j]] _ x > > print(z[[j]]) > } > z > } > #------------------------------------------ > > Replacing the line that assigns z[[j]] with the following 2 lines produces > the expected result > > y _ x > z[[j]] _ y > > Furthermore, I get the expected result by running the function under Splus > 6.Um, you're not telling us what you're expecting, nor what you're getting, nor what is supposedly wrong, nor which version of R this relates to, nor the operating system.... Running your code (after removing the tab and underscore damage) I get exactly the same result with or without the intermediate assignment. -- O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._