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James R. Milks

2007-Jul-02 03:15 UTC

[R] Extracting sums for individual factors in data frames

I have a data frame with two columns, one of which is a factor  
(Species) and the other is numeric (BA, which stands for basal  
area).  Here's a sample:


Species	BA
ACSA	55.7632696
FRAM	122.9933524
ACSA	67.54424205
ACSA	89.22123136
ACSA	82.46680716
ACSA	22.46238747
ACSA	19.94911335
ACSA	20.42035225
ACSA	19.00663555
ACSA	21.67698931
ACSA	57.80530483
ACSA	30.31636911
Dead	43.98229715
Dead	40.21238597
Dead	16.49336143
Dead	40.21238597
Dead	16.49336143
ACSA	78.53981634
VIPR	3.926990817
AEGL	11.78097245
AEGL	0
AEGL	0
ACSA	0
ACSA	0
ACSA	0
VIPR	0

I would like to calculate relative basal area for each species in  
this plot.  For that, I need to divide the total basal area per  
species by the total basal area in the plot.  Getting the total basal  
area in the plot is easy.  However, I'm mystified on how to get the  
total basal area per species.  Is there a way to extract and/or sum  
the total basal area per species?

Thank you in advance.

Jim Milks

Graduate Student
Environmental Sciences Ph.D. Program
Wright State University
3640 Colonel Glenn Hwy
Dayton, OH 45435

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Rolf Turner

2007-Jul-02 03:30 UTC

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[R] Extracting sums for individual factors in data frames

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jim holtman

2007-Jul-02 03:34 UTC

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[R] Extracting sums for individual factors in data frames

Does this do what you want?
> x <- "Species BA+ ACSA    55.7632696
+ FRAM    122.9933524
+ ACSA    67.54424205
+ ACSA    89.22123136
+ ACSA    82.46680716
+ ACSA    22.46238747
+ ACSA    19.94911335
+ ACSA    20.42035225
+ ACSA    19.00663555
+ ACSA    21.67698931
+ ACSA    57.80530483
+ ACSA    30.31636911
+ Dead    43.98229715
+ Dead    40.21238597
+ Dead    16.49336143
+ Dead    40.21238597
+ Dead    16.49336143
+ ACSA    78.53981634
+ VIPR    3.926990817
+ AEGL    11.78097245
+ AEGL    0
+ AEGL    0
+ ACSA    0
+ ACSA    0
+ ACSA    0
+ VIPR    0"> x <- read.table(textConnection(x), header=TRUE)
> # compute area for each species
> y <- tapply(x$BA, x$Species, sum)
> # get ratio
> y/sum(x$BA)       ACSA        AEGL        Dead        FRAM        VIPR
0.656210104 0.013678643 0.182746672 0.142805034
0.004559548>
>


On 7/1/07, James R. Milks <james.milks@wright.edu>
wrote:>
> I have a data frame with two columns, one of which is a factor
> (Species) and the other is numeric (BA, which stands for basal
> area).  Here's a sample:
>
>
> Species BA
> ACSA    55.7632696
> FRAM    122.9933524
> ACSA    67.54424205
> ACSA    89.22123136
> ACSA    82.46680716
> ACSA    22.46238747
> ACSA    19.94911335
> ACSA    20.42035225
> ACSA    19.00663555
> ACSA    21.67698931
> ACSA    57.80530483
> ACSA    30.31636911
> Dead    43.98229715
> Dead    40.21238597
> Dead    16.49336143
> Dead    40.21238597
> Dead    16.49336143
> ACSA    78.53981634
> VIPR    3.926990817
> AEGL    11.78097245
> AEGL    0
> AEGL    0
> ACSA    0
> ACSA    0
> ACSA    0
> VIPR    0
>
> I would like to calculate relative basal area for each species in
> this plot.  For that, I need to divide the total basal area per
> species by the total basal area in the plot.  Getting the total basal
> area in the plot is easy.  However, I'm mystified on how to get the
> total basal area per species.  Is there a way to extract and/or sum
> the total basal area per species?
>
> Thank you in advance.
>
> Jim Milks
>
> Graduate Student
> Environmental Sciences Ph.D. Program
> Wright State University
> 3640 Colonel Glenn Hwy
> Dayton, OH 45435
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@stat.math.ethz.ch 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

What is the problem you are trying to solve?

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Simon Blomberg

2007-Jul-02 04:24 UTC

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[R] Extracting sums for individual factors in data frames

Does this do what you want?
> with(dat, tapply(BA, Species, sum))      ACSA       AEGL       Dead       FRAM       VIPR 
565.172518  11.780972 157.393792 122.993352   3.926991 

Cheers,

Simon.

On Sun, 2007-07-01 at 23:15 -0400, James R. Milks wrote:> I have a data frame with two columns, one of which is a factor  
> (Species) and the other is numeric (BA, which stands for basal  
> area).  Here's a sample:
> 
> 
> Species	BA
> ACSA	55.7632696
> FRAM	122.9933524
> ACSA	67.54424205
> ACSA	89.22123136
> ACSA	82.46680716
> ACSA	22.46238747
> ACSA	19.94911335
> ACSA	20.42035225
> ACSA	19.00663555
> ACSA	21.67698931
> ACSA	57.80530483
> ACSA	30.31636911
> Dead	43.98229715
> Dead	40.21238597
> Dead	16.49336143
> Dead	40.21238597
> Dead	16.49336143
> ACSA	78.53981634
> VIPR	3.926990817
> AEGL	11.78097245
> AEGL	0
> AEGL	0
> ACSA	0
> ACSA	0
> ACSA	0
> VIPR	0
> 
> I would like to calculate relative basal area for each species in  
> this plot.  For that, I need to divide the total basal area per  
> species by the total basal area in the plot.  Getting the total basal  
> area in the plot is easy.  However, I'm mystified on how to get the  
> total basal area per species.  Is there a way to extract and/or sum  
> the total basal area per species?
> 
> Thank you in advance.
> 
> Jim Milks
> 
> Graduate Student
> Environmental Sciences Ph.D. Program
> Wright State University
> 3640 Colonel Glenn Hwy
> Dayton, OH 45435
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at stat.math.ethz.ch 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.-- 
Simon Blomberg, BSc (Hons), PhD, MAppStat. 
Lecturer and Consultant Statistician 
Faculty of Biological and Chemical Sciences 
The University of Queensland 
St. Lucia Queensland 4072 
Australia

Room 320, Goddard Building (8)
T: +61 7 3365 2506 
email: S.Blomberg1_at_uq.edu.au 

The combination of some data and an aching desire for 
an answer does not ensure that a reasonable answer can 
be extracted from a given body of data. - John Tukey.

Norm.Good at csiro.au

2007-Jul-10 00:16 UTC

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[R] Extracting sums for individual factors in data frames

Try this I used today

 

aggregate(data, by=list(factor.name=data$FACTOR.NAME), sum)

 

Norm Good

CMIS/e-Health Research Centre

A joint venture between CSIRO and the Queensland Government

Lvl 20, 300 Adelaide Street BRISBANE QLD 4000
PO Box 10842 Adelaide Street BRISBANE QLD 4000

Ph: 07 3024 1640 Fx: 07 3024 1690 
Em: norm.good@csiro.au  Web: http://e-hrc.net/ 

 


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