[R] prblem with NA

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 06.01.2009 02:29:18:

> Hello -
> 
> kayj wrote:
> > 
> > Hi all
> > 
> > I have a data set with the total number of columns =ncol, and the 
total
> > number of rows=nrow. I am trying to loop over the values and id the 
value is
> > less than or equal to 100 to be changed to 1. if the value is greater 
than
> > 100 , to be changed to 0. if NA , let X[i,j]=NA. I ran into a problem 
where
> > if one row in my data set had all values =NA, then the program does 
not
> > continue working past that row! 
> > 
> > At some point I get the following error message:
> > 
> > “Error in if (data [i, j] <= 100) { : missing value where TRUE/FALSE 
needed”
> > 
> > Here is the program 
> > 
> > data<-read.table("fileName.txt", header=F, sep='\t')
> > 
> > X=data
> > for(i in ncol)
> > {
> > for(j in nrow)
> > {
> > if(data[i,j]<=100) {X[i,j]=1}
> > if(data[i,j]>100) {X[i,j]=0}
> > 
> > if(is.na(data[i,j])) {X[i,j]=NA}
> > }
> > }
> 
> 
> An alternate, vectorized solution may be:
> 
> X <- ifelse(data <= 100, 1, 0)

Another one

X <-(da<=100)*1

Logical vectors can be treated like numeric with TRUE=1 and FALSE=0, I 
learned that somewhere but it is not mentioned in help page for ?logical 
so it is not so easy to find.

Regards
Petr 




> 
> And as 'data' is a function in the utils package include with R, you 
> might consider not naming your variables 'data'.
> 
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