[R] counting missing values

[Liaw, Andy]

> From: Uwe Ligges [mailto:ligges at statistik.uni-dortmund.de]
> 
> vincent.stoliaroff at socgen.com wrote:
> 
> > Hello R lovers
> > I have written a little cute function to count the number 
> of missing value
> > per row in a matrix and return the percentage of missing value
> > 
> > it takes a lot of time to run with a 1000 rows matrix
> > 
> > I'd like to know if there is a function already implemented 
> to count the
> > number of occurence of a given values in a vector
> > 
> > 
> > For information,
> > here is the function
> > count<-0
> > for (i in 1:nrow(Matrix))
> >       {
> >       for (j in 1:ncol(Matrix)) {if (is.na(Matrix[i,j])) 
> count<-count+1}
> >       Result[i,1]<-((count/(ncol(Matrix)))*100);
> >       count<-0
> >       }
> > Result
> > 
> > thanks for any help
> > Vincent
> 
> Well, it's pretty easy to do it:
> 
> apply(Matrix, 1, function(x) sum(is.na(x))) / ncol(Matrix) * 100

Or perhaps faster:

  rowMeans(is.na(Matrix)) * 100

Andy

 
> Uwe Ligges
> 
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