-----Original Message-----
From: Roberto Lodeiro Muller <roberto.mul...@doctor.com>
To: roberto.mul...@doctor.com
Sent: Mon, Mar 21, 2011 3:37 pm
Subject: Re: [R] Computing row differences in new columns
Sorry, my data appeared badly formatted to me, so I converted it to plain text:
And just to clarify, for each subject in the first row it should appear the
difference to the next row, so that the last entry on each subject would be a
NA.
Thanks again for your help
Roberto
SUBJECT DATE RESULT DateDiff ResultDiff
10751 22-Jul-03 3.5
10751 13-Feb-04 1.3
10751 20-Aug-04 1.6
10751 08-Mar-05 1.7
10751 30-Aug-05 1.6
10751 21-Feb-06 1.3
10751 31-Aug-06 1.2
10751 27-Feb-07 1.5
10751 29-Aug-07 1
10752 29-Jul-03 5.9
10752 24-Feb-04 5
10752 25-Aug-04 3.6
10752 11-Mar-05 5.1
10752 18-Sep-05 2.2
10752 23-Feb-06 3.1
10752 24-Aug-06 3.7
10752 27-Feb-07 6
-----Original Message-----
From: Roberto Lodeiro Muller <roberto.mul...@doctor.com>
To: r-help@r-project.org
Sent: Mon, Mar 21, 2011 3:23 pm
Subject: [R] Computing row differences in new columns
i
I have the following columns with dates and results, sorted by subject and
date.
'd like to compute the differences in dates and results for each patient, based
n the previous row. Obviously the last entry for each subject should be a NA.
Which would be the best way to accomplished that ?
I guess questions like that have been already answered a thousand times, so I
pologize for asking one more time.
Thanks
Roberto
SUBJECT
ate
esult
ateDiff
esultDiff
10751
2-Jul-03
.5
0751
3-Feb-04
.3
10751
0-Aug-04
.6
10751
8-Mar-05
.7
10751
0-Aug-05
.6
10751
1-Feb-06
.3
10751
1-Aug-06
.2
10751
7-Feb-07
.5
10751
9-Aug-07
10752
9-Jul-03
.9
10752
4-Feb-04
10752
5-Aug-04
.6
10752
1-Mar-05
.1
10752
8-Sep-05
.2
10752
3-Feb-06
.1
10752
4-Aug-06
.7
10752
7-Feb-07
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
