[R] variable colnames
COMTE Guillaume
g.comte at alliance-ir.net
Wed May 17 10:05:17 CEST 2006
Hy all,
I apologize i've used rownames instead of colnames in my first exemple. (that's why i changed the mail object) I was on mars when i wrote my question...
Every answer where correct ... but, because i've made a wrong question, people wern't able to understand...
So finally i'm speaking about colnames :
Let's be more precise:
I've got a query that gives me for a given serial number the names of errors that has occurs for this serial.
I've got a loop that retrieve data's from a database for each errors that has occurs.
In my loop i tag colnames with the name of the error, in order to access them later (when i've finished to get all data's) so the colnames are like this (i extract a table of 5 columns, the number of rows is variable and doesn't matter):
Nom_
Cpt_
Tfth_
Ftm_
Fts_
Just after the "_" i paste the error name (the error names are without spaces or numbers)
By example if the error name is "InletPressureToLow" the colnames will be
"Nom_InletPressureToLow"
"Cpt_InletPressureToLow"
...
So i'm forging the colnames, and once i've done that i'm unable to access them again if i do like that (nomalarme1 contain errors names without number and spaces):
For (i in 1:length(nomalarme1))
nom_nom=paste("nom_",nomalarme1[i],sep="")
nom_cpt=paste("cpt_",nomalarme1[i],sep="")
nom_tfth=paste("tfth_",nomalarme1[i],sep="")
nom_ftm=paste("ftm_",nomalarme1[i],sep="")
nom_fts=paste("fts_",nomalarme1[i],sep="")
All of these vars contains valid colnames, but are view as character by R not a colnames, and i didn't find any way to cast it or else in order to make R show me the data's that are attached to the colname, or that R understand that it is not the characters that i'm looking for but the keyword that identify the name i've given to a column.
I've got another idea on how to do that (without using colnames has described in the answers), but i'm still interested if it exist a way to access colnames values by assigning to a var a colname name then using the var (the var contain the name of the column) to retieve the values...
Thks all.
COMTE Guillaume
-----Message d'origine-----
De : Christoph Buser [mailto:buser at stat.math.ethz.ch]
Envoyé : mardi 16 mai 2006 18:32
À : r-help at stat.math.ethz.ch
Cc : COMTE Guillaume
Objet : Re: [R] variable row names
Hi
I was confused by your example, too and still am a little bit
confused, so please excuse me if my example does not answer your
question:
You have a data.frame "dat"
> dat <- data.frame(colname1 = 1:4, colname2 = 5:8)
You have a vector with the colnames of "dat"
> namen <- colnames(dat)
You want to acess on the values in dat bu using the vector "namen"
> for (i in namen)
> print(dat[,i])
or
> for (i in 1:length(namen))
> print(dat[,namen[i]])
Does that answer your question or is it more complicated?
Best regards,
Christoph
--------------------------------------------------------------
Christoph Buser <buser at stat.math.ethz.ch>
Seminar fuer Statistik, LEO C13
ETH Zurich 8092 Zurich SWITZERLAND
phone: x-41-44-632-4673 fax: 632-1228
http://stat.ethz.ch/~buser/
--------------------------------------------------------------
COMTE Guillaume writes:
> Thks for your answer,
>
> I wish to access colnames by using vars like in my example nom="toto" , if i type toto in R it will display the column named toto with the values that the column keep, i wish the same by typing nom, but in my case it shows the content of the var nom not the values of the column named toto, but "toto".
>
> I can't be more accurate because i'm unable to formulate it an other way.
>
> another example:
>
> I've got a set of colnames :
>
> > nomalarme1
> [1] "AirFlowFailure" "AirSensorFailure" "GasLeek"
> [4] "SuddenPressureDrop" "InletPressureToLow" "PressureRiseFailure"
> [7] "HoseLeakTestFailure" "o50DCVoltageToLow"
>
> All of these names identify colnames (like AirFlowFailure).
>
> My problem is if i do
>
> For (i in 1:length(nomalarme1))
> {
> nomalarme1[i]
> }
> It will display the names of the columns not the datas, is there is something that can tell R to show data's that have for colname nomalarme[i], and not just the colname.
>
>
> Thks for your answer, i've looked into S-Poetry and it seems that it isn't explained there, but my "poor" english maybe have missed it...
>
>
> COMTE Guillaume
>
>
>
>
>
> -----Message d'origine-----
> De : Patrick Burns [mailto:pburns at pburns.seanet.com]
> Envoyé : mardi 16 mai 2006 17:12
> À : COMTE Guillaume
> Objet : Re: [R] variable row names
>
> I don't understand your question, but perhaps the
> subscripting section of chapter 1 of S Poetry can
> help you.
>
>
> Patrick Burns
> patrick at burns-stat.com
> +44 (0)20 8525 0696
> http://www.burns-stat.com
> (home of S Poetry and "A Guide for the Unwilling S User")
>
> COMTE Guillaume wrote:
>
> >Hy all,
> >
> >
> >
> >I wish to use a variable as rownames for a set of datas.
> >
> >
> >
> >By example :
> >
> >
> >
> >
> >
> >
> >
> >>nom<-"toto"
> >>
> >>
> >
> >
> >
> >>prenom<-"tutu"
> >>
> >>
> >
> >
> >
> >>res<-c(1,2)
> >>
> >>
> >
> >
> >
> >>res<-t(res)
> >>
> >>
> >
> >
> >
> >>res
> >>
> >>
> >
> > [,1] [,2]
> >
> >[1,] 1 2
> >
> >
> >
> >>colnames(res)<-c(nom,prenom)
> >>
> >>
> >
> >
> >
> >>res
> >>
> >>
> >
> > toto tutu
> >
> >[1,] 1 2
> >
> >
> >
> >>nom
> >>
> >>
> >
> >[1] "toto"
> >
> >
> >
> >
> >
> >
> >I wish to call the rowname by the variable name, in this case it would
> >be < nom > or < prenom > , but if i do that it gives me the name of the
> >row not the values of it.
> >
> >
> >
> >Is this possible or not?
> >
> >
> >
> >Thks all.
> >
> >
> >
> >COMTE Guillaume
> >
> >
> >
> >
> > [[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
> >
> >
> >
> >
>
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