R help - Feb 2011 - combining two columns into one column despite NAs

I am trying to combine two columns in a data frame into one column.  Some
values in either column are missing, but not in the same row for the two
different columns.  Additionally, when both columns in a row contain data,
the data are identical.  I want a new column with the identical data or the
data from the column with observed data.  For example:

I have
>data
           id   x    y
       1   a   1   NA
       2   b   2    2
       3   c   3    3
       4   d  NA  4

And I want
>new.data
           id   x    y     z
       1   a   1   NA   1
       2   b   2    2     2
       3   c   3    3     3
       4   d  NA  4     4

I've looked through the help and there are column combining solutions, but
they don't seem to work well for this solution.
Thanks for any help!
Andy

	[[alternative HTML version deleted]]

I think the easiest way is probably

data$z <- rowMeans(data[, c("x", "y")], na.rm=TRUE)

Best,
Ista

On Fri, Feb 25, 2011 at 12:12 AM, Andrew Anglemyer
<andrew.anglemyer at gmail.com> wrote:
> I am trying to combine two columns in a data frame into one column. ?Some
> values in either column are missing, but not in the same row for the two
> different columns. ?Additionally, when both columns in a row contain data,
> the data are identical. ?I want a new column with the identical data or the
> data from the column with observed data. ?For example:
>
> I have
>>data
> ? ? ? ? ? id ? x ? ?y
> ? ? ? 1 ? a ? 1 ? NA
> ? ? ? 2 ? b ? 2 ? ?2
> ? ? ? 3 ? c ? 3 ? ?3
> ? ? ? 4 ? d ?NA ?4
>
> And I want
>>new.data
> ? ? ? ? ? id ? x ? ?y ? ? z
> ? ? ? 1 ? a ? 1 ? NA ? 1
> ? ? ? 2 ? b ? 2 ? ?2 ? ? 2
> ? ? ? 3 ? c ? 3 ? ?3 ? ? 3
> ? ? ? 4 ? d ?NA ?4 ? ? 4
>
> I've looked through the help and there are column combining solutions,
but
> they don't seem to work well for this solution.
> Thanks for any help!
> Andy
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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>


-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org