On Jan 19, 2012, at 6:42 PM, jamesrobinsonjnr wrote:
I have a panel data set defined as a simple data.frame with a factor
age and
income. I would like to generate the results of a set function such
as (sum,
mean, or even diff) separate for each factor (category or age group).
However I want the result to have the same dimension as the overal
data.frame. Therefore, I expect to get repeaded the same result for
each
item within a category, but different accross categories.
Eg:
age income avg_inc
20 100 100
20 90 100
20 110 100
30 200 200
30 250 200
30 150 200
?ave (which returnsf the same length as the first argument.)
?tapply
?aggregate (neither which will yield that same number of items
(There are also the doBy and plyr packages.)
What builtin function can assist in doing this without my having to
write
loops. I know in Eviews there is the sumsby, meansby, minsby and so
forth.
--
David Winsemius, MD
West Hartford, CT
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