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Discarding a matrix based on the rowSums value

4 messages · Juan Antonio Balbuena, R. Michael Weylandt, Sarah Goslee +1 more

Juan Antonio Balbuena
# 
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.

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}
	}
}

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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R. Michael Weylandt
# 
any()

Michael
On Mon, Nov 21, 2011 at 10:58 AM, Juan Antonio Balbuena <balbuena at uv.es> wrote:
Sarah Goslee
# 
Hi,

You write below:
And in fact, ?any is just what you need, as you said.

any(SUMROW == N.1s)

should do the trick.

Sarah
On Mon, Nov 21, 2011 at 10:58 AM, Juan Antonio Balbuena <balbuena at uv.es> wrote:

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      David Winsemius
    

    

      
      #
    

  


  

      
On Nov 21, 2011, at 10:58 AM, Juan Antonio Balbuena wrote:

        

            

      
      
      
    

        
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.)

            

      
      
      
    

        
rowSums retruns a vector, whereas if() only works with vectors of  
length 1.

Perhaps you want:

flag <-  ifelse(SUMROW == N.1s, TRUE, FALSE)   #?

            

      
      
      
    

        

      
      
    

        
David Winsemius, MD
West Hartford, CT