[R] Extract NA data rows

[David Scott]

On 25/01/2011 8:07 p.m., typhoong wrote:
>
> hi i have the following dataframe
>
> x	y
> 1	345
> 6	NA
> 8	123
> 32	123
> 12	NA
> 6	124
> 7	NA
>
> and i want to extract the data rows which contains "NA" data, I tried
>
> subset(dataframe,y=="NA")
>
> but fail. if you know the answers, please let me know thanks.
>
> typhoong
>

Your test is wrong for NA. You must use is.na:

 > df
    x   y
1  1 345
2  6  NA
3  8 123
4 32 123
5 12  NA
6  6 124
7  7  NA
 > subset(df, is.na(y))
    x  y
2  6 NA
5 12 NA
7  7 NA


-- 
_________________________________________________________________
David Scott	Department of Statistics
		The University of Auckland, PB 92019
		Auckland 1142,    NEW ZEALAND
Phone: +64 9 923 5055, or +64 9 373 7599 ext 85055
Email:	d.scott at auckland.ac.nz,  Fax: +64 9 373 7018

Director of Consulting, Department of Statistics