[R] Trying to understand how to sort a DF on two columns

Bert Gunter bgunter@4567 @end|ng |rom gm@||@com
Tue Aug 13 04:35:43 CEST 2019


Do a web search on "How does order() work R" or similar for more.

I can't explain with() any better than the docs: saying that it evaluates
the expression argument in the data argument environment -- a data frame
for the data frame method -- probably won't help you.

-- Bert

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Mon, Aug 12, 2019 at 7:20 PM Sorkin, John <jsorkin using som.umaryland.edu>

> 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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