Hello,
Though good answers were already given, I would like to say something.
1.
If you are lazy (typing), use with, if you prefer to play safe, don't.
I am lazy many times, but in interactive mode only.
2.
I find it better in the long run *not* to take advantage of R's
one-liners, they tend to be less readable. Instead of putting everything
in the same instruction why not
i <- order( temp$patid, temp$time )
data4xsort <- temp[ i, ]
This has the disadvantage of creating an extra variable but are you
really having memory problems? If not, use the clearer code. Besides, if
this goes into a function all temporary variables will be gone and the
memory released, in which case there will be no problem.
(The with equivalent is i <- with(temp, order(patid, time)), btw.)
Hope this helps,
Rui Barradas
Às 03:20 de 13/08/19, Sorkin, John escreveu:
I want to sort a DF, temp, on two columns, patid and time. I have searched the
internet and found code that I was able to modify to get my data sorted.
Unfortunately I don't understand how the code works. I would appreciate it if
someone could explain to me how the code works. Among other questions, despite
reading, I don't understand how with() works, nor what it does in the current
setting.
code:
data4xsort<-temp[
with( temp, order(temp[,"patid"], temp[,"time"])),
]
Thank you,
John
John David Sorkin M.D., Ph.D.
Professor of Medicine
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology and Geriatric
Medicine
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)
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