On Jan 19, 2010, at 10:57 PM, rusers.sh wrote:
Hi,
I know we can use 1:10 to represent the 1,2,3,...,10 numbers, but the
following conditions are except.
Anybody knows how to represent the following two cases with similar
usage
of ":" or others? Usually, i will get several hundred names for
them, such
as a1,a2,... or f[[1]],f[[2]],...
#Example data
a1<-array(1:12,c(2,3,2)); a2<-array(2,c(2,3,2)); a3<-array(0,c(2,3,2))
> agb <-array( , dim=c(3,2,3,2))
> agb[1,,,] <- a1
> agb[2,,,] <- a2
> agb[3,,,] <- a3
> agb[1:3 , 1, 2, 1]
[1] 3 2 0
a1[1,2,1]:a3[1,2,1]
[1] 3 2 1 0
#the correct result should be 3,2,0
So the method of using "a1[i,j,k]:a3[i,j,k]" to represent
"c(a1[i,j,k],a2[i,j,k],a3[i,j,k])" is not correct?
Yes, not correct.
##For lists with matrices as its elements
f<-list()
f[[1]]<-a1;f[[2]]<-a2;f[[3]]<-a3
f[[1]][1,2,1]:f[[3]][1,2,1]
[1] 3 2 1 0
#the correct result should be 3,2,0
So the method of using "f[[1]][i,j,k]:f[[3]][i,j,k]" to represent
"f[[1]][i,j,k],f[[2]][i,j,k],f[[3]][i,j,k])" is not correct?
In both your examples the interpreter reduces the expression to 3:0
and that results in 3 2 1 0
I noticed that the above two methods have got the same results,
although
not correct. So i guess i have made the same errors in them. Is
there some
method to represent them concisely?
Any ideas about them?
Thanks a lot.
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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