R help - Jul 2010 - define subgroups based on position in table

Dear list,
 
I have a data frame with one column (group) and want to add a second column
(sub) with a serial number that says to which subgroup a cell belongs. A
subgroup contains the consecutive rows of the same group. The number of a
subgroup is based on its position in the table. The first subgroup of A's
and B's should have nr A1 and B1, the second nr A2 and B2, etc.. I hope the
example below makes things more clear.
This is what my data look like:
 
x <- read.table(textConnection("group
A
A
A
B    
B
A
A
B 
B
B
A
A"),header=TRUE)
closeAllConnections()
 
   group
1      A
2      A
3      A
4      B
5      B
6      A
7      A
8      B
9      B
10     B
11     A
12     A
 
This is what it should become:
 
   group sub
1      A A1
2      A A1
3      A A1
4      B B1
5      B B1
6      A A2
7      A A2
8      B B2
9      B B2
10     B B2
11     A A3
12     A A3
 
 

 

Maarten Stevens

Senior onderzoeker - Aquatisch Beheer / Senior scientist - Aquatic Management 

 

INBO – Instituut voor Natuur- en Bosonderzoek / Research Institute for Nature
and Forest

Afdeling Beheer en Duurzaam Gebruik / Dept. Management and Sustainable Use

Kliniekstraat 25 Ÿ B-1070 Brussels, BELGIUM

E-mail: maarten.stevens@inbo.be <mailto:maarten.stevens@inbo.be> 

Phone: +32.2.558.19.18 Ÿ Gsm / Cell: +32.492.72.28.97 Ÿ Fax: +32.2.558.18.05 Ÿ
www.inbo.be <http://www.inbo.be/>

 

 

 

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	[[alternative HTML version deleted]]

try this:
> x <- read.table(textConnection("group
+ A
+ A
+ A
+ B
+ B
+ A
+ A
+ B
+ B
+ B
+ A
+ A"),header=TRUE, as.is=TRUE)
> closeAllConnections()
> # use rle to get the 'runs'
> x.rle <- rle(x$group)
> # now generate the group numbers
> x.grp <- ave(x.rle$values, x.rle$values, FUN=seq_along)
> # put the numbers back
> x$sub <- with(x.rle, paste(rep(values, lengths), rep(x.grp, lengths),
sep=''))
>
>
> x
   group sub
1      A  A1
2      A  A1
3      A  A1
4      B  B1
5      B  B1
6      A  A2
7      A  A2
8      B  B2
9      B  B2
10     B  B2
11     A  A3
12     A  A3
>

On Tue, Jul 20, 2010 at 8:02 AM, STEVENS, Maarten
<Maarten.STEVENS at inbo.be> wrote:
> Dear list,
>
> I have a data frame with one column (group) and want to add a second column
(sub) with a serial number that says to which subgroup a cell belongs. A
subgroup contains the consecutive rows of the same group. The number of a
subgroup is based on its position in the table. The first subgroup of A's
and B's should have nr A1 and B1, the second nr A2 and B2, etc.. I hope the
example below makes things more clear.
> This is what my data look like:
>
> x <- read.table(textConnection("group
> A
> A
> A
> B
> B
> A
> A
> B
> B
> B
> A
> A"),header=TRUE)
> closeAllConnections()
>
> ? group
> 1 ? ? ?A
> 2 ? ? ?A
> 3 ? ? ?A
> 4 ? ? ?B
> 5 ? ? ?B
> 6 ? ? ?A
> 7 ? ? ?A
> 8 ? ? ?B
> 9 ? ? ?B
> 10 ? ? B
> 11 ? ? A
> 12 ? ? A
>
> This is what it should become:
>
> ? group sub
> 1 ? ? ?A A1
> 2 ? ? ?A A1
> 3 ? ? ?A A1
> 4 ? ? ?B B1
> 5 ? ? ?B B1
> 6 ? ? ?A A2
> 7 ? ? ?A A2
> 8 ? ? ?B B2
> 9 ? ? ?B B2
> 10 ? ? B B2
> 11 ? ? A A3
> 12 ? ? A A3
>
>
>
>
>
> Maarten Stevens
>
> Senior onderzoeker - Aquatisch Beheer / Senior scientist - Aquatic
Management
>
>
>
> INBO ? Instituut voor Natuur- en Bosonderzoek / Research Institute for
Nature and Forest
>
> Afdeling Beheer en Duurzaam Gebruik / Dept. Management and Sustainable Use
>
> Kliniekstraat 25 ? B-1070 Brussels, BELGIUM
>
> E-mail: maarten.stevens at inbo.be <mailto:maarten.stevens at
inbo.be>
>
> Phone: +32.2.558.19.18 ? Gsm / Cell: +32.492.72.28.97 ? Fax:
+32.2.558.18.05 ? www.inbo.be <http://www.inbo.be/>
>
>
>
>
>
>
>
> Druk dit bericht a.u.b. niet onnodig af.
> Please do not print this message unnecessarily.
>
> Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver
weer
> en binden het INBO onder geen enkel beding, zolang dit bericht niet
bevestigd is
> door een geldig ondertekend document. The views expressed in ?this message
> and any annex are purely those of the writer and may not be regarded as
stating
> an official position of INBO, as long as the message is not confirmed by a
duly
> signed document.
>
> ? ? ? ?[[alternative HTML version deleted]]
>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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