On Mar 17, 2011, at 11:40 PM, Sebastián Daza wrote:
Hi everyone,
Is there any command to identify the pattern of responses of a
database with this format:
year id
2008 1
2009 1
2008 2
2009 2
2008 3
2009 3
2008 4
2009 4
2010 4
Two methods assuming this is in a a data.frmae named `dat` and you
want cross-tabulation:
tapply(dat$year, dat$id, length)
`xtabs` offers a more flexible method
xtabs(year ~ id, data=dat)
--
David.
I just need the frequency of the patterns grouped by id:
2008 2009 2010 = 80
I don't understand what format this might be specifying. If you offer
an example you should also specify the correct output from that
example rather than the output from a larger example whose content you
make the reader guess at. I cannot see any connection between the
numbers 80, 30, and 10 with the example above, nor cann is see a
connection with the set 2008, 2009, and 2010 with anything other than
the set of objects associated with id==4. So its possible that the
first step in your desired process might be the split function.
> split(dat, dat$id)
$`1`
year id
1 2008 1
2 2009 1
$`2`
year id
3 2008 2
4 2009 2
$`3`
year id
5 2008 3
6 2009 3
$`4`
year id
7 2008 4
8 2009 4
9 2010 4
)
2009 2010 = 30
2008 2009 = 10
and so on....
Thank you in advance!
--
David Winsemius, MD
West Hartford, CT
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