[R] Extracting dataframe rows containing NAs in one column

[Pete Brecknock]

kaallen wrote:
> 
> Hi,
> 
> I am working on a data set which looks like this:
> 
>> head(temp)
>   Day Month Year   PW  ROW
> 1   1     1 1959   NA 6.40
> 2   2     1 1959 6.65 6.35
> 3   3     1 1959 2.50 3.60
> 4   4     1 1959 0.60 2.25
> 5   5     1 1959 0.85 0.30
> 6   6     1 1959 0.00 2.20
> 
> I am trying to extract all the rows containing NA. I can extrat all the
> rows without NAs in column 4 using 
> 
>> PWna<-temp[complete.cases(temp[,4]),]
>> head(PWna)
>   Day Month Year   PW  ROW
> 2   2     1 1959 6.65 6.35
> 3   3     1 1959 2.50 3.60
> 4   4     1 1959 0.60 2.25
> 5   5     1 1959 0.85 0.30
> 6   6     1 1959 0.00 2.20
> 7   7     1 1959 1.40 1.65
> 
> But can't figure out how to extract the rows WITH the NAs. Can anyone
> advise me?
> 
> Thanks in advance
> 

I am sure others will have cleaner approaches but how about ....

# Data
temp = data.frame(Day=1:6,Month=1, Year=c(NA,1959,NA,1959,1959,1959),
PW=c(6,7,8,NA,10,11))

# Extract Any Row Containing an NA
myNAs = temp[apply(temp,1,function(x) any(is.na(x))),]

HTH

Pete


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