[R] NA's in if statement

[michael watson (IAH-C)]

Some careful use of is.na() may help.
Either by using it to remove NA values or as part of the if statement.
 
Or:
 
my.wdir <- na.omit(dat$wdir)
for(i in 1:length(my.wdir)) {
 
#etc

	-----Original Message----- 
	From: r-help-bounces at stat.math.ethz.ch on behalf of lindsayv at unbc.ca 
	Sent: Fri 2/11/2005 9:34 PM 
	To: r-help at stat.math.ethz.ch 
	Cc: 
	Subject: [R] NA's in if statement
	
	

	Hello,
	
	I am having trouble dealing with NA values in if statements such as:
	i<-1
	for(i in 1:length(dat$wdir)){
	if (dat$wspd[i]==0){
	dat$wdir[i]<-0
	}
	}
	
	I get the following error due to the presence of NS values in the data:
	Error in if (dat$wspd[i] == 0) { : missing value where TRUE/FALSE needed
	
	Sorry if this is an old question but I was unable to resolve this from the
	info on na.action etc. or old archives.
	
	Thank you for any suggestions,
	
	Vera Lindsay
	
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