
-----Original Message-----
From: Roberto Lodeiro Muller <roberto.muller@doctor.com>
To: roberto.muller@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.muller@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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