On Apr 2, 2010, at 3:39 PM, Geoffrey Smith wrote:
Hello, I have an unbalanced panel data set that looks like:
ID,YEAR,HEIGHT
Tom,2007,65
Tom,2008,66
Mary,2007,45
Mary,2008,50
Harry,2007,62
Harry,2008,62
James,2007,68
Jack,2007,70
Jordan,2008,72
That is, James, Jack, and Jordan are missing a YEAR.
Is there any command that will "fill in" the missing YEAR such that
the end
result will be balanced and look like:
ID,YEAR,HEIGHT
Tom,2007,65
Tom,2008,66
Mary,2007,45
Mary,2008,50
Harry,2007,62
Harry,2008,62
James,2007,68
James,2008,NA
Jack,2007,70
Jack,2008,NA
Jordan,2007,NA
Jordan,2008,72
It's not "one command" but it's an approach ... assumes you have data
in a dataframe named ftbl:
> fexp <- expand.grid(ID=unique(ftbl$ID), YEAR=unique(ftbl$YEAR))
> merge(fexp, ftbl, all=TRUE)
ID YEAR HEIGHT
1 Harry 2007 62
2 Harry 2008 62
3 Jack 2007 70
4 Jack 2008 NA
5 James 2007 68
6 James 2008 NA
7 Jordan 2007 NA
8 Jordan 2008 72
9 Mary 2007 45
10 Mary 2008 50
11 Tom 2007 65
12 Tom 2008 66
--
David Winsemius, MD
West Hartford, CT
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