[R] na.action

[Tony Plate]

Maybe this does what you want:

 > x <- as.matrix(read.table("clipboard"))
 > x
   V1 V2 V3 V4
1 NA  0  0  0
2  0 NA  0 NA
3  0  0 NA  2
4  0  0  2 NA
 > rowSums(x==2, na.rm=T)
1 2 3 4
0 0 1 1
 >

There's probably at least 5 or 6 other quite sensible ways of doing 
this, but this is probably the fastest (and the least versatile).

A more general building block is the sum() function, as in:

 > sum(x[3,]==2, na.rm=T)
[1] 1
 >

The key is the use of the 'na.rm=T' argument value.

hope this helps,

Tony Plate


Tim Smith wrote:
> Hi,
>  
> I had the following code:
> 
>   testp <- rcorr(t(datcm1),type = "pearson")
>   mat1 <- testp[[1]][,] > 0.6
>   mat2 <- testp[[3]][,] < 0.05
>   mat3 <- mat1 + mat2
>  
> The resulting mat3 (smaller version) matrix looks like:
>  
>  NA   0    0    0  
>   0  NA    0   NA 
>   0   0   NA    2 
>   0   0    2   NA   
>  
> To get to the number of times a '2' appears in the rows, I was trying to run the following code:
>  
> numrow = nrow(mat3)
>   counter <- matrix(nrow = numrow,ncol =1)
>   for(i in 1:numrow){
>    count = 0;
>    for(j in 1:numrow){
>     if(mat3[i,j] == 2){
>      count = count + 1
>     }
>    }
>           counter[i,1] = count
>   }
>  
> However, I get the following error:
>  
> 'Error in if (mat3[i, j] == 2) { : missing value where TRUE/FALSE needed'
>  
> I also tried to use the na.action, but couldn't get anything. I'm sure there must be a relatively easy fix to this. Is there a workaround this problem?
>  
> thanks,
>  
> Tim
>  
> 
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