I want to know where all the NAs are in a matrix. The data frame looks like this:> vmc[1:5,]date year month day snow.new prcp tmin snow.dep tmax 1 01NOV1954 1954 11 1 NA NA -14.44444 NA 12.2222222 2 02NOV1954 1954 11 2 NA NA -13.88889 NA 2.2222222 3 03NOV1954 1954 11 3 NA NA -16.66667 NA -1.1111111 4 04NOV1954 1954 11 4 NA NA NA NA -0.5555556 5 05NOV1954 1954 11 5 NA NA -17.22222 NA -2.7777778 tmean yearmo 1 -1.111111 195411 2 -5.833333 195411 3 -8.888889 195411 4 NA 195411 5 -10.000000 195411>This does not work:> subset(vmc, snow.new==NA)[1] date year month day snow.new prcp tmin snow.dep [9] tmax tmean yearmo <0 rows> (or 0-length row.names) Because:> NA==NA[1] NA How can I return all rows of this data frame that contain NA in a particular field? Thanks, Ben Osborne -- Botany Department University of Vermont 109 Carrigan Drive Burlington, VT 05405
Benjamin M. Osborne allegedly said on 2/25/2005 10:33 AM:> I want to know where all the NAs are in a matrix. The data frame looks like > this: > > >>vmc[1:5,] > > date year month day snow.new prcp tmin snow.dep tmax > 1 01NOV1954 1954 11 1 NA NA -14.44444 NA 12.2222222 > 2 02NOV1954 1954 11 2 NA NA -13.88889 NA 2.2222222 > 3 03NOV1954 1954 11 3 NA NA -16.66667 NA -1.1111111 > 4 04NOV1954 1954 11 4 NA NA NA NA -0.5555556 > 5 05NOV1954 1954 11 5 NA NA -17.22222 NA -2.7777778 > tmean yearmo > 1 -1.111111 195411 > 2 -5.833333 195411 > 3 -8.888889 195411 > 4 NA 195411 > 5 -10.000000 195411 > > > This does not work: > >>subset(vmc, snow.new==NA) > > [1] date year month day snow.new prcp tmin snow.dep > [9] tmax tmean yearmo > <0 rows> (or 0-length row.names) > > > Because: > >>NA==NA > > [1] NA > > How can I return all rows of this data frame that contain NA in a particular > field? > > Thanks, > Ben Osborne >Ben, This is a perfect job for ?complete.cases. You should also read Introduction to R, pg. 9-10 in the PDF document, regarding how missing values are handled in R. --sundar
See ?is.na Uwe Ligges Benjamin M. Osborne wrote:> I want to know where all the NAs are in a matrix. The data frame looks like > this: > > >>vmc[1:5,] > > date year month day snow.new prcp tmin snow.dep tmax > 1 01NOV1954 1954 11 1 NA NA -14.44444 NA 12.2222222 > 2 02NOV1954 1954 11 2 NA NA -13.88889 NA 2.2222222 > 3 03NOV1954 1954 11 3 NA NA -16.66667 NA -1.1111111 > 4 04NOV1954 1954 11 4 NA NA NA NA -0.5555556 > 5 05NOV1954 1954 11 5 NA NA -17.22222 NA -2.7777778 > tmean yearmo > 1 -1.111111 195411 > 2 -5.833333 195411 > 3 -8.888889 195411 > 4 NA 195411 > 5 -10.000000 195411 > > > This does not work: > >>subset(vmc, snow.new==NA) > > [1] date year month day snow.new prcp tmin snow.dep > [9] tmax tmean yearmo > <0 rows> (or 0-length row.names) > > > Because: > >>NA==NA > > [1] NA > > How can I return all rows of this data frame that contain NA in a particular > field? > > Thanks, > Ben Osborne >
Have you considered "is.na"?
My favorite tool for answering questions like this is
www.r-project.org -> search -> "R site search". When I asked
there for
"subsetting by NA" just now, I got 101 hits, the third of which
mentioned "is.na". Also, the posting guide
"R-project.org/posting-guide.html" gives other useful tips for how to
find information about R.
hope this helps. spencer graves
Benjamin M. Osborne wrote:
>I want to know where all the NAs are in a matrix. The data frame looks like
>this:
>
>
>
>>vmc[1:5,]
>>
>>
> date year month day snow.new prcp tmin snow.dep tmax
>1 01NOV1954 1954 11 1 NA NA -14.44444 NA 12.2222222
>2 02NOV1954 1954 11 2 NA NA -13.88889 NA 2.2222222
>3 03NOV1954 1954 11 3 NA NA -16.66667 NA -1.1111111
>4 04NOV1954 1954 11 4 NA NA NA NA -0.5555556
>5 05NOV1954 1954 11 5 NA NA -17.22222 NA -2.7777778
> tmean yearmo
>1 -1.111111 195411
>2 -5.833333 195411
>3 -8.888889 195411
>4 NA 195411
>5 -10.000000 195411
>
>
>
>This does not work:
>
>
>>subset(vmc, snow.new==NA)
>>
>>
> [1] date year month day snow.new prcp tmin snow.dep
> [9] tmax tmean yearmo
><0 rows> (or 0-length row.names)
>
>
>Because:
>
>
>>NA==NA
>>
>>
>[1] NA
>
>How can I return all rows of this data frame that contain NA in a particular
>field?
>
>Thanks,
>Ben Osborne
>
>
>