R Error : DATA to MATRIX

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

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R Error : DATA to MATRIX

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