R help - Sep 2006 - Transformation of a data frame

Dear R-helpers,

Apologies in advance for this (probably) simple question.  I've searched the
R Archive and can't seem to find a solution to my problem.  

I have a data frame of vegetation quadrat data with the following format:

Q S C
1 A 5
1 B 10
1 C 50
1 D 10
2 A 20
2 E 10
2 C 40
3 D 5
3 F 1
3 G 5
3 B 75

Where Q is the sample (vegetation quadrats), S is the species and C is the
percentage cover of each species within the sample.  I wish to transform
this into a community data matrix for analysis within the vegan package,
which needs the following data frame format:

Q A  B  C  D  E  F  G
1 5  10 50 10 0  0  0
2 20 0  40 0  10 0  0
3 0  75 0  5  0  1  75

I can't manage to do this transformation so your help would be much
appreciated.  Thanks very much in advance.

All the best,
Des

one approach is to use reshape(), e.g.,

# suppose that 'dat' is your data.frame, then
res <- reshape(dat, direction = "wide", idvar = "Q",
timevar = "S")
res[is.na(res)] <- 0
res


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Des Callaghan" <descall at blueyonder.co.uk>
To: <r-help at stat.math.ethz.ch>
Sent: Tuesday, September 12, 2006 8:43 AM
Subject: [R] Transformation of a data frame

> Dear R-helpers,
>
> Apologies in advance for this (probably) simple question.  I've 
> searched the
> R Archive and can't seem to find a solution to my problem.
>
> I have a data frame of vegetation quadrat data with the following 
> format:
>
> Q S C
> 1 A 5
> 1 B 10
> 1 C 50
> 1 D 10
> 2 A 20
> 2 E 10
> 2 C 40
> 3 D 5
> 3 F 1
> 3 G 5
> 3 B 75
>
> Where Q is the sample (vegetation quadrats), S is the species and C 
> is the
> percentage cover of each species within the sample.  I wish to 
> transform
> this into a community data matrix for analysis within the vegan 
> package,
> which needs the following data frame format:
>
> Q A  B  C  D  E  F  G
> 1 5  10 50 10 0  0  0
> 2 20 0  40 0  10 0  0
> 3 0  75 0  5  0  1  75
>
> I can't manage to do this transformation so your help would be much
> appreciated.  Thanks very much in advance.
>
> All the best,
> Des
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
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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.
> 

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