R array loops

"E. Anthon Eff" <eaeff@mtsu.edu> 
Date:   Tue, February 8, 2011 2:34 pm 
To:   drwhite@uci.edu   

0

Subject: Re: NA vs NaN From: "E. Anthon Eff" <eaeff@mtsu.edu> Date: Tue, February 8, 2011 3:57 pm To: drwhite@uci.edu Options: View Full Header | View Printable Version | Download this as a file | View Message Details | View as HTML

Doug: found this at http://cran.r-project.org/doc/manuals/R-intro.html

       Note that there is a second kind of "missing" values which are
       produced by numerical computation, the so-called Not a Number,
       NaN, values. Examples are

        > 0/0

       or

        > Inf - Inf

       which both give NaN since the result cannot be defined sensibly.

       In summary, is.na(xx) is TRUE both for NA and NaN values. To
       differentiate these, is.nan(xx) is only TRUE for NaNs. Missing
       values are sometimes printed as <NA> when character vectors are
       printed without quotes.

So it seems that there is no need to convert NaN to NA (I never have). But, if you want to do it, something like this should work:

for (i in NCOL(sccs)) {

 z<-which(is.nan(sccs[,i]))
 is.na(sccs[z,i])<-TRUE
 }

1

A loop like this should work (but didn't get a chance to test it):

for (i in c("v108","v110","v112","v146")) {
z<-which(sccs[,i]==0)
is.na(sccs[z,i])<-TRUE
}

2

On 2/8/2011 3:38 PM, drwhite@uci.edu wrote:
> Super, got it. Many thanks!
>> Doug, if the DoL variable is "q":
>>
>> z<-which(q==0)
>> is.na(q[z])<-TRUE
>>
>> Now the "0" values have been replaced by NA
> AND IF I Wanted to do this in a list?
>
>   q1<-sccs$v108
>   z<-which(q1==0)
>   is.na(q1[z])<-TRUE
>
>   q2<-sccs$v110
>   z<-which(q2==0)
>   is.na(q2[z])<-TRUE
>
>   q3<-sccs$v112
>   z<-which(q3==0)
>   is.na(q3[z])<-TRUE
>
>   q4<-sccs$v111
>   z<-which(q4==0)
>   is.na(q4[z])<-TRUE
>
>   q5<-sccs$v146
>   z<-which(q5==0)
>   is.na(q5[z])<-TRUE
>
>   depvar<- q0
>   my_sccs<-data.frame(
>   dep_var=q0,
>   #prepsoil=sccs$v109,
>   clearland=q1,
>   plantcrop=q2,
>   #sccs$v110,
>   harvest=q3,
>   #sccs$v112,
>   tendcrop=q4,
>   #sccs$v111,
>   carry=q5,
>   #sccs$v146,
>   #fetchwater=sccs$v125,
>   #prepveg=sccs$v116,
>   #cook=sccs$v121,
>   plow=(sccs$v243>1)*1,
>   extwar=sccs$v892   #no comma
>   )