On Nov 21, 2011, at 10:58 AM, Juan Antonio Balbuena wrote:
Hello
I would appreciate your help on the followig. I want to generate
random
binary matrices but I need to discard those with all-1 rows. That
is, for a
10x10 matrix with five 1's
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 0 0 0 0 0 0 0 0 0 1
[2,] 0 0 0 0 0 0 1 0 0 0
[3,] 0 0 0 0 0 0 1 0 0 0
[4,] 0 0 0 0 0 0 0 0 0 0
[5,] 0 0 0 0 0 0 0 0 0 0
[6,] 0 0 0 0 0 0 0 0 0 0
[7,] 0 0 0 0 0 0 0 0 0 0
[8,] 0 0 0 0 0 0 0 0 0 0
[9,] 0 0 0 0 0 0 0 0 0 0
[10,] 0 0 0 0 0 1 1 0 0 0
would be passed on to further computations, whereas
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 0 0 0 0 0 0 0 0 0 0
[2,] 0 0 0 0 0 0 0 0 0 0
[3,] 0 0 0 0 0 0 0 0 0 0
[4,] 0 0 0 0 0 0 0 0 0 0
[5,] 0 0 0 0 0 0 0 0 0 0
[6,] 0 0 0 0 0 0 0 0 0 0
[7,] 0 0 0 0 0 0 0 0 0 0
[8,] 0 0 0 0 0 0 0 0 0 0
[9,] 0 0 0 0 0 0 0 0 0 0
[10,] 0 1 0 1 0 1 1 0 0 1
must be discarded.
Why? it has no rows that meet your verbal description " all-1
rows" (Nor it would meet your code implementation below, but I offer a
suggestion in case you want only to exclude matrices with exactly rows
whose sum is 5 but would accept those with sums of 4, or 6, etc.)
For any N.1s <= Nrow, I am trying
Nrow = 10
Ncol = 10
N.1s = 5
flag <- TRUE
while (flag == TRUE) {
m <- matrix ((sample (c(rep(1, each=N.1s), rep(0,
each=((Ncol*Nrow)-N.1s))))), Nrow)
SUMROW <- rowSums(m)
if (SUMROW == N.1s) {flag <- TRUE} else {flag <- FALSE}
rowSums retruns a vector, whereas if() only works with vectors of
length 1.
Perhaps you want:
flag <- ifelse(SUMROW == N.1s, TRUE, FALSE) #?
}
}
but I get this warning
Warning message:
In if (SUMROW == N.1s) { :
the condition has length > 1 and only the first element will be used
What I specifically need is a way to write "If any of the elements
of the
SUMROW vector == N.1s then flag <-true else flag<-false".
Any help would be much appreciated.
--
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