Re: [R] dates are shown as X15.Feb.03

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Wed 28 Sep 2005 - 02:36:32 EST

On 9/27/2005 12:13 PM, Chris Buddenhagen wrote:
> Dear Duncan Murdoch
>
> Thanks for responding. I will provide more complete info with future
> questions. The data for a small pilot study are below.
>
> The values for each month are the percentage cover of an invasive plant here
> in the Galapagos (TT=treatment) type = immediately herbicide applied or
> applied to regrowth later. I called the data glyphosate.txt.
>
>
> The code is
>
> glyp<-read.delim("C:\\Chris\\active projects\\Aristolochia\\glyphosate.txt",
> header=T)
> list(names(glyp))
>
> This is the output that mystified me:
>
> [1] "TT" "type" "CUADRANTES" "X15dec02" "X15jan03"
> [6] "X15feb03" "X15apr03" "X15jun03" "X15aug03" "X15oct03"

It looks as though you have column headings like "15dec02". That's not a legal R variable name, so it prepends the X to make it into one. That way you can do things like glyp$X15dec02 to extract that column. glyp$15dec02 would give a syntax error.

>
> While I have an expert on hand I have another question, how do I produce a
> graph of time against percentage cover with error bars. I wanted to only
> present months on the x axis. I start by reorganizing the data using this:

Various functions implement error bars, but I haven't used them in a long time, so I'll leave this question for someone else to answer.

Duncan Murdoch

>
> glyp2<-reshape(glyp, direction="long", idvar=c("TT", "type",
> "CUADRANTES"),varying=list(names(glyp)[4:10]),v.names="cover") but couldn't
> get month names to appear in the column time.
>
>
>
> TT type CUADRANTES "15dec02" "15jan03" "15feb03"
> "15apr03" "15jun03" "15aug03" "15oct03"
> T1 immediate 1 63 59 60 55 4.5 1
> 2
> T1 immediate 2 75 75 75 75 6.5 1
> 2
> T1 immediate 22 72 70 70 65 35 2
> 3.5
> T1 immediate 26 90 80 80 75 17.5 2
> 4
> T1 immediate 33 75 80 85 85 40 1
> 2
> T2 immediate 18 85 80 80 22.5 2.5 2
> 5
> T2 immediate 21 90 85 85 60 16.5 0
> 1
> T2 immediate 23 85 80 80 75 17.5 1
> 2
> T2 immediate 28 90 85 85 27.5 27.5 0
> 1
> T2 immediate 31 90 85 85 9 12.5 1
> 2
> T3 immediate 3 50 58 60 65 35 1
> 2
> T3 immediate 10 63 60 60 15 2.5 0
> 10
> T3 immediate 12 90 85 85 17.5 15 0
> 5
> T3 immediate 16 85 82 80 78 9 1
> 1.5
> T3 immediate 34 75 80 85 85 35 1.5
> 2.5
> T4 wait 4 75 75 75 7.5 2.5 0 0
> T4 wait 11 63 60 60 12.5 2.5 1 2
> T4 wait 24 90 85 80 3.5 5.5 1 2
> T4 wait 29 85 80 80 1.5 4.5 1 2
> T4 wait 32 85 80 80 3.5 4.5 2 3.5
> T5 wait 6 50 50 50 1 1 0.5 2
> T5 wait 14 80 75 75 15 5.5 1 2
> T5 wait 15 90 80 80 1 5.5 1 3
> T5 wait 20 85 80 80 22.5 8.5 0 0
> T5 wait 25 85 80 80 22.5 8.5 1 1.5
> T6 wait 8 75 75 75 1.5 4.5 0 1.5
> T6 wait 9 90 85 85 1.5 3.5 1 2
> T6 wait 13 80 75 75 1 3.5 1 1.5
> T6 wait 19 90 85 80 1 2.5 1 2
> T6 wait 27 85 80 75 1 3.5 1 2
> Tc control 5 50 45 45 40 23 20 25
> Tc control 7 50 53 54 55 55 50 55
> Tc control 17 90 80 70 22.5 9 15 20
> Tc control 30 75 75 70 75 45 60 70
> Tc control 35 90 85 80 85 65 60 70
>
> Chris Buddenhagen, Botany Department, Charles Darwin Research Station, Santa
> Cruz,Galapagos. Mail: Charles Darwin Foundation, Casilla 17-01-3891 Avenida
> 6 de Diciembre N36-109 y Pasaje California Quito, ECUADOR
>
>
>
>
>
>
> ______________________________________________________________________
> EL CONTENIDO DE ESTE MENSAJE ES DE ABSOLUTA RESPONSABILIDAD DEL AUTOR.
> FUNDACION CHARLES DARWIN
> WWW.DARWINFOUNDATION.ORG



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