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result NA , but expected True or False

5 messages · Ragia Ibrahim, David Winsemius, PIKAL Petr +1 more

Ragia Ibrahim
# 
Dear Group,
Kindly,

I have those two lines
if(  (z_nebla==0) ||  (z_nebla_dash==0) )
           CM <- 0         else             
            
               CM <-  0.5 *(1/a)  +   0.5*(1/b)  

when running it

I got this

z_nebla==0)
logical(0)
logical(0)
[1] NA


why  (z_nebla==0) ||  (z_nebla_dash==0)
gives me NA ?

thanks in advance
Ragia
Ragia Ibrahim
# 
Dear Group,
Kindly,
 I have the following 

Common_Friends <- intersect(node_neighbours_i_out,node_neighbours_j_out)
         class(Common_Friends)
         print(Common_Friends)
         #4 = Common_Friends
       newline<-c(i,   Common_Friends  )
 df<- rbind(df,newline)

I created a data frame to add the new line

when   Common_Friends  =0 nothing add ?, how to force it to write the value into the data frame


Common_Friends <- intersect(node_neighbours_i_out,node_neighbours_j_out)
[1] "numeric"
numeric(0)
[1] 5
thanks in advance
Ragia
David Winsemius
#
On Aug 9, 2015, at 8:45 PM, Ragia Ibrahim wrote:

            

      
      
      
    

        
We should instead ask you: why should a logical-OR give anything other than NA when given two length-zero vectors as arguments?

 What value do you expect?

            

      
      
      
    

        

      
      
    

        
David Winsemius
Alameda, CA, USA

  
  


  


      

    

    

      
      

        


  

        

      PIKAL Petr
    

    

      
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Hi

Your question is without reproducible example and I find it a bit cryptic. You do not uncover what is i. If it is a number I wonder why your atempts fail.

Find answer in line below.

            

      
      
      
    

        
Common_Friends is not 0 but an empty vector.

            

      
      
      
    

        
[1] 1

            

      
      
      
    

        
a          b
1 1 -0.7346253
2 2  0.2063677
3 3  0.8580852
4 4 -0.4844313
5 5  5.0000000

            

      
      
      
    

        
so there is 5th line added but as b is empty vector the length of newline is one and recycling rule applies. If you want add zero you have to declare it as a zero (or NA) and not as an empty vector e.g.

            

      
      
      
    

        
[1] 0

Cheers
Petr

            

      
      
      
    

        

      
      
    

        
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      William Dunlap
    

    

      
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The || operator will always return a result of type 'logical' and length 1.
You gave it two operands of length 0, so it returned the logical value NA,
meaning it had no idea what the result should be.  If you give it operands
of length > 1, it will use the only the first elements of them.  (S and S+
considered length 0 operands to || and && an error and warned about
length>1 operands, but R makes no comment about either case).

Perhaps you want to use the | operator, which acts like == and +, returning
a result as long as the longer of its operands, unless one operand has zero
elements, in which case it returns a length 0 result.


Bill Dunlap
TIBCO Software
wdunlap tibco.com

        
On Sun, Aug 9, 2015 at 8:45 PM, Ragia Ibrahim <ragia11 at hotmail.com> wrote: