Message-ID: <43316EBA.3060206@pdf.com>
Date: 2005-09-21T14:31:22Z
From: Spencer Graves
Subject: factor as seq() in for loop
In-Reply-To: <1127151294.432ef6beb14d7@www2.helsinki.fi>
Does the follow help?
> aFactor <- factor(rep(letters[1:3], 1:3))
> aFactor
[1] a b b c c c
Levels: a b c
> for(af in levels(aFactor)){
+ print(sum(aFactor==af))
+ }
[1] 1
[1] 2
[1] 3
spencer graves
Tord Snall wrote:
> Dear all,
> I would like to use the values in vegaggr.BLMCMR02$colony
>
> str(vegaggr.BLMCMR02)
> `data.frame': 1678 obs. of 3 variables:
> $ vegtype : Factor w/ 27 levels "2010","2020",..: 3 4 5 19 4 5 19 5
> $ colony : Factor w/ 406 levels "0","1","10","100",..: 1 1 1 1 2 2 2
> $ Totvegproparea: num 0.00055 0.03956 0.95705 0.00284 0.05215 ...
>
> as the seq in a for loop (for(var in seq)), and therefore first picked them
> out as
> cols = aggregate(list(A = vegaggr.BLMCMR02$Totvegproparea),
> list(colony = vegaggr.BLMCMR02$colony), sum)[,1]
>
>>str(cols)
>
> Factor w/ 406 levels "0","1","10","100",..: 1 2 3 4 5 6 7 8 9 10 ...
>
> I next planned to transform cols using as.integer(cols). However, this
> transformation gives a vector corresponding to seq(from=1,to=length(cols)).
>
> Could someone please give advice on how to make use of a factor as the seq
> in a for loop (which is strictly not allowed' according to ?Control).
>
> Thanks!
>
> Tord
>
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--
Spencer Graves, PhD
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