R help - Mar 2012 - R Error : DATA to MATRIX

Dear Sir/Madam,

I'm getting a problem with a R-code which converts a data frame to a matrix.

It first generate a (m^(n-m) * m) matrix A and then regenerate another
matrix B having less dimension than A which satisfy some condition. Now I
wish to assign each row of B to a vector as individual.

My problem is when I set any choice of (n,m) except m=1 it works fine but
setting m=1 I got the error : Error in B[i, ] : incorrect number of
dimensions.

Moreover if (n,m) is large (say, (20,8)) I got the error : Error: cannot
allocate vector of size 3.0 Gb. I know this is due to large dimension of
matrix A. How to solve this problem.

My code is given below:

**********************************************************************

n=5
m=3
R=numeric(0)
# Generate all possible m-tuple ( variables having range 0 to n  ) in a (
m^(n-m) * m ) matrix

r = expand.grid(rep(list(0:(n-m)), m))

write.table(r,file="test.txt",row.names=FALSE,col.names=FALSE)

a= read.table(file="test.txt",sep="",header=FALSE)

A= data.matrix(a)

#.........................................................................................

# Generate matrix whose rowsum = n-m

meet.crit = apply(A, 1, function(.row) any((sum(.row)) == n-m))      # 
criteron for being rowsum = n

cbind(A, meet.crit)                                                  # 
Checking rowsum = n for each row
-m
B=A[meet.crit,]                                                      # 
Generate matrix

#.........................................................................................


for(i in 1:choose(n-1,m-1)){
R=B[i,]
}

***************************************************************************

Can you please help me how to get rid of these errors. Thanking you in
advance.

Regards

Ritwik Bhattacharya


Senior Research Fellow
SQC & OR UNIT, KOLKATA
INDIAN STATISTICAL INSTITUTE

Voice : +91 9051253944

This mail is scanned by Ironport

Hi

See in text.
> 
> Dear Sir/Madam,
> 
> I'm getting a problem with a R-code which converts a data frame to a 
matrix.
> 
> It first generate a (m^(n-m) * m) matrix A and then regenerate another
> matrix B having less dimension than A which satisfy some condition. Now 
I
> wish to assign each row of B to a vector as individual.
> 
> My problem is when I set any choice of (n,m) except m=1 it works fine 
but
> setting m=1 I got the error : Error in B[i, ] : incorrect number of
> dimensions.
> 
> Moreover if (n,m) is large (say, (20,8)) I got the error : Error: cannot
> allocate vector of size 3.0 Gb. I know this is due to large dimension of
> matrix A. How to solve this problem.
> 
> My code is given below:
> 
> **********************************************************************
> 
> n=5
> m=3
> R=numeric(0)
> # Generate all possible m-tuple ( variables having range 0 to n  ) in a 
(
> m^(n-m) * m ) matrix
> 
> r = expand.grid(rep(list(0:(n-m)), m))
> 
> write.table(r,file="test.txt",row.names=FALSE,col.names=FALSE)
> 
> a= read.table(file="test.txt",sep="",header=FALSE)
Above lines do not do any sensible things. r shall be same as a.
> 
> A= data.matrix(a)
> 
> 
#.........................................................................................
> 
> # Generate matrix whose rowsum = n-m
> 
> meet.crit = apply(A, 1, function(.row) any((sum(.row)) == n-m))      # 
> criteron for being rowsum = n
No error
> 
> cbind(A, meet.crit)                                                  # 
> Checking rowsum = n for each row
> -m
> B=A[meet.crit,]                                                      # 
No error
> Generate matrix
> 
> 
#.........................................................................................
> 
> 
> for(i in 1:choose(n-1,m-1)){
> R=B[i,]
> }
No error. However in each cycle only ith row is added to R and therefore 
only last row (in this case B[6,]) is added and stays in R. Either you 
need to use

R <- c(R, B[i,])

in your construction or better as B is matrix
> class(B)
[1] "matrix"

you can transform it to vector easily by stripping dimensions.

 R<-t(B)
> dim(R) <-NULL
> R
 [1] 2 0 0 1 1 0 0 2 0 1 0 1 0 1 1 0 0 2

Regards
Petr

> 
> 
***************************************************************************
> 
> Can you please help me how to get rid of these errors. Thanking you in
> advance.
> 
> Regards
> 
> Ritwik Bhattacharya
> 
> 
> Senior Research Fellow
> SQC & OR UNIT, KOLKATA
> INDIAN STATISTICAL INSTITUTE
> 
> Voice : +91 9051253944
> 
> This mail is scanned by Ironport
> 
> ______________________________________________
> 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.

On Mar 23, 2012, at 2:53 AM, ritwik_r at isical.ac.in wrote:
> Dear Sir/Madam,
>
> I'm getting a problem with a R-code which converts a data frame to a  
> matrix.
>
> It first generate a (m^(n-m) * m) matrix A and then regenerate another
> matrix B having less dimension than A which satisfy some condition.  
> Now I
> wish to assign each row of B to a vector as individual.
>
> My problem is when I set any choice of (n,m) except m=1 it works  
> fine but
> setting m=1 I got the error : Error in B[i, ] : incorrect number of
> dimensions.
>
> Moreover if (n,m) is large (say, (20,8)) I got the error : Error:  
> cannot
> allocate vector of size 3.0 Gb. I know this is due to large  
> dimension of
> matrix A. How to solve this problem.
>
> My code is given below:
>
> **********************************************************************
>
> n=5
> m=3
> R=numeric(0)
> # Generate all possible m-tuple ( variables having range 0 to n  )  
> in a (
> m^(n-m) * m ) matrix
>
> r = expand.grid(rep(list(0:(n-m)), m))
>
> write.table(r,file="test.txt",row.names=FALSE,col.names=FALSE)
>
> a= read.table(file="test.txt",sep="",header=FALSE)
>
> A= data.matrix(a)
>
>
#.........................................................................................
>
> # Generate matrix whose rowsum = n-m
>
> meet.crit = apply(A, 1, function(.row) any((sum(.row)) == n-m))      #
> criteron for being rowsum = n
>
> cbind(A, meet.crit)                                                  #
> Checking rowsum = n for each row
> -m
> B=A[meet.crit,]
At this point the default behavior of the "[" function is to return a
vector rather than a matrix. You need to add drop=FALSE as an  
additional argument. Read the help page for ?"[".

                                  #
> Generate matrix
>
>
#.........................................................................................
>
>
> for(i in 1:choose(n-1,m-1)){
> R=B[i,]
> }
>
> ***************************************************************************
>
> Can you please help me how to get rid of these errors. Thanking you in
> advance.
>
> Regards
>
> Ritwik Bhattacharya
>
>
> Senior Research Fellow
> SQC & OR UNIT, KOLKATA
> INDIAN STATISTICAL INSTITUTE
-- 

David Winsemius, MD
West Hartford, CT