[R] how to overlook the zero in the denominator
Adaikalavan Ramasamy
ramasamy at cancer.org.uk
Wed Jul 27 11:19:00 CEST 2005
The simplest way would be to ignore them in the sum
sum( ( x - y )/x, na.rm=T )
and notice that I have utilised the vectorised operation. But if you
want to, you can explicitly remove them with
good <- which( x != 0 )
sum( ( x[good] - y[good] )/ x[good] )
Regards, Adai
On Wed, 2005-07-27 at 16:51 +0800, Chun-Ying Lee wrote:
> Dear R users:
>
> I have two set of data, as follow:
> x<-c(0,0,0.28,0.55,1.2,2,1.95,1.85,
> 1.6,0.86,0.78,0.6,0.21,0.18)
> y<-c(0,0,0,0.53,1.34,1.79,2.07,1.88,
> 1.52,0.92,0.71,0.55,0.32,0.19)
> i<-1:length(x)
>
> I want to sum each (x[i]-y[i])^2/x[i] together,
> like:
> >Sum <-sum((x[i]-y[i])^2/x[i])
> >Sum
> [1] NaN
>
> Because the denominator shoud not be zero.
> So I want to overlook those when x[i]=0,
> and just to sum those x[i] not equal to 0.
> What should I do?
> Any suggestion.
> Thanks in advance !!
>
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