[R] re shaping "long-form" longitudinal data from sql query

[Gabor Grothendieck]

If DF is your data frame then create a time column like this:

DF$time <- ave(DF$DaysAgo, DF$PID, FUN = seq_along)

and now use the reshape command on DF (or melt/cast
from the reshape package).

On Thu, Apr 24, 2008 at 2:13 PM, Tubin <sredmonson at yahoo.com> wrote:
>
> hi, I'm a total noob who is having to ramp up to full speed very quickly due
> to an unfortunate abrupt staffing change at my job :)
>
> I have longitudinal data that looks like this:
>               PID             OBSDATE                DaysAgo CleanValue
> NAME
> 1  1410164934000610  8/17/2004 13:03:38    1345        6.2        HGBA1C
> 2  1410164934000610 11/16/2004 10:39:51    1254        7.1        HGBA1C
> ...etc
>
> I'd like to end up with a wide-format table like:
> PID     OBSDATE.1    DaysAgo.1    CleanValue.1 [...] OBSDATE.n   DaysAgo.n
> CleanValue.n
>
> The problem:  Every patient's on a different schedule, so there's no natural
> timevar value to reshape with.
>
> My solution involved creating another column for the timevar and looping
> through the dataframe to populate that column with correct values; however,
> it's a pretty big table and so the loop runs really slowly.  I need to do
> this particular operation on quite a few datafiles on a regular basis, and
> my database keeps getting bigger - so I anticipate this solution won't be
> ideal in the future.
>
> Can anyone recommend a more efficient solution?
>
> --
> View this message in context: http://www.nabble.com/reshaping-%22long-form%22-longitudinal-data-from-sql-query-tp16851308p16851308.html
> Sent from the R help mailing list archive at Nabble.com.
>
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