[R] sometimes removing NAs from code

[Marc Schwartz]

On Oct 26, 2011, at 10:25 AM, Schatzi wrote:

> Sometimes I have NA values within specific columns of a dataframe (in this
> example, the first two columns can have NAs). If there are NA values, I
> would like them to be removed.
> 
> I have been using the code:
> 
> y<-c(NA,5,4,2,5,6,NA)
> z<-c(NA,3,4,NA,1,3,7)
> x<-1:7
> adata<-data.frame(y,z,x)
> adata<-adata[-which(apply(adata[,1:2],1,function(x)any(is.na(x)))),]
> 
> This works well if there are NA values, but when a dataset doesn't have NA
> values, this code messes up the dataframe. I was trying to pick apart this
> code and could not understand why it didn't work when there were no NA
> values.
> 
> 
> If there are no NA values and I run just the part:
> apply(adata[,1:2],1,function(x)any(is.na(x)))
> it results in:
>    2     3     5     6 
> FALSE FALSE FALSE FALSE 
> 
> I was thinking that I can put in an if statement, but I think there has to
> be a better way.
> 
> Any ideas/help? Thank you.


Presuming that you want to remove an entire row, if any of the elements in that row are NA's, see ?na.omit

> na.omit(adata)
  y z x
2 5 3 2
3 4 4 3
5 5 1 5
6 6 3 6

HTH,

Marc Schwartz