[R] adding NA to "subset"

[Sherri Heck]

Hi All-

I have a data set (spdco2)

 > spdco2
      [,1] [,2]     [,3]
 [1,]    1  5.4 382.4212
 [2,]    2  5.1 383.0315
 [3,]    3  4.8 383.9520
 [4,]    4  4.7 384.4376
 [5,]    5  4.7 384.5929
 [6,]    6  4.4 384.8864
 [7,]    7  4.1 385.2156
 [8,]    8  3.8 385.2919
 [9,]    9  3.7 385.5925
[10,]   10  3.9 385.6801


I am subsetting it to output when [,2] is >= 4.7 . 

x<-subset(spdco2,spdco2[,2]>=4.7)

This works, but I would like to add 'NA' to the data that it does 
exclude based on my subset criteria.  I have searched through the 
archives and two R books, but I cannot figure out how to add the NA.
Any suggestions would be appreciated-

thanks!

sherri





x<-subset(spdco2,spdco2[,2]>=4.7)