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

Sorkin, John j@ork|n @end|ng |rom @om@um@ry|@nd@edu
Tue Aug 13 04:44:29 CEST 2019


Thank you for your reply (and the many other questions to the list that you answer).

I understand how order works when ordering based on a single column. What I don’t understand is how the code I included with my email works. I believe my problem is a lack of understanding of what with does. I have read about the with function, but I must be missing something.

Thank you,

From: Bert Gunter <bgunter.4567 using gmail.com>
Sent: Monday, August 12, 2019 10:36 PM
To: Sorkin, John <jsorkin using som.umaryland.edu>
Cc: r-help using r-project.org (r-help using r-project.org) <r-help using r-project.org>
Subject: Re: [R] Trying to understand how to sort a DF on two columns


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<mailto:jsorkin using som.umaryland.edu>> wrote:
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.

  with( temp, order(temp[,"patid"], temp[,"time"])),

Thank you,

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
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)

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