[R] how to overlook the zero in the denominator

[Dimitris Rizopoulos]

look at ?sum() and use the `na.rm' argument, i.e.,

sum((x - y)^2 / x, na.rm = TRUE)

I hope it helps.

Best,
Dimitris

p.s., R is vectorized, you don't have to use `x[i]' in your example.

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Chun-Ying Lee" <u9370004 at cc.kmu.edu.tw>
To: <r-help at stat.math.ethz.ch>
Sent: Wednesday, July 27, 2005 10:51 AM
Subject: [R] how to overlook the zero in the denominator


> 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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