Re: [R] Using data frames for EDA: Insert, Change name, delete columns? (Newcomer's question)

From: ronggui <0034058_at_fudan.edu.cn>
Date: Wed 29 Jun 2005 - 03:02:54 EST

if i want to rename the data frame,say data1,to data2,have i use those
>data2<-data1
>rm(dat1)

or these is simpler way to do this? thank you !

On Tue, 28 Jun 2005 10:08:55 -0500
"Earl F. Glynn" <efg@stowers-institute.org> wrote:

> "Ben Fairbank" <BEN@SSANET.COM> wrote in message
> news:CA612484A337C6479EA341DF9EEE14AC03AC1BB5@hercules.ssainfo...
>
> > I ... cannot find commands to easily insert,
> > remove (delete), rename, and re-order (arbitrarily, not sort) columns.
> ...
> > Could a reader provide a reference where such commands are
> > documented?
>
> There's a lot of info in the old R-Help postings, but searching and finding
> an answer for a particular problem can be a bit of a pain.
> Here's some info from some old R-Help postings that may help on your
> question:
>
> DELETE TWO COLUMNS
> -------------------------------------------------------
> I have a dataframe 'd2004' and I want to remove two columns:
> 'd2004$concentration' and 'd2004$stade".
>
> I could do it just as follows:
>
> > names(d2004)
>
> [1] "Localite" "Date" "parcelle" "maille"
> "presence.plant" "concentration" "stade.culture"
> [8] "stade" "Trou" "Horizon" "Profondeur"
>
> > d2004 <- d2004[, -c(6, 8)]
>
> but I'd like to use column names (to avoid finding column numbers each
> time).
>
> I cannot find an easy way to operate...
>
> I wonder why that works:
> > d2004[, "concentration"]
>
> and this don't:
> > d2004 <- d2004[, -c("concentration", "stade")]
>
>
>
> SOLUTIONS:
>
> d2004$concentration <- NULL
> d2004$stade <- NULL
>
> or
>
>
>
> Newdata <- subset(d2004, select=-c(concentration,stade))
>
>
>
>
>
>
>
> RENAMING COLUMNS
> -------------------------------------------------------
> This is a sample data frame:
>
> > myData <- data.frame( col1 = 1:3, col2 = 2:4, col3 = 3:5 )
>
> > myData
>
> col1 col2 col3
>
> 1 1 2 3
>
> 2 2 3 4
>
> 3 3 4 5
>
>
>
> You can change all names by:
>
> > names( myData )<- c( "newcol1", "newcol2", "newcol3" )
>
> > myData
>
> newcol1 newcol2 newcol3
>
> 1 1 2 3
>
> 2 2 3 4
>
> 3 3 4 5
>
>
>
> Or a single name by:
>
> > names( myData )[ 2 ] <- "newcol2"
>
> > myData
>
> col1 newcol2 col3
>
> 1 1 2 3
>
> 2 2 3 4
>
> 3 3 4 5
>
>
>
> Or if you know the name, but not the column number:
>
> > names( myData )[ which( names( myData ) == "newcol2" ) ] <- "verynewcol2"
>
> > myData
>
> col1 verynewcol2 col3
>
> 1 1 2 3
>
> 2 2 3 4
>
> 3 3 4 5
>
>
>
> REORDERING COLUMNS
> -------------------------------------------------------
> I don't have a clipping for this one, but here's what I'd try:
>
> > myData <- data.frame( col1 = 1:3, col2 = 2:4, col3 = 3:5 )
> >
> > myData
> col1 col2 col3
> 1 1 2 3
> 2 2 3 4
> 3 3 4 5
> > MyData <- myData[,c(3,1,2)]
> > MyData
> col3 col1 col2
> 1 3 1 2
> 2 4 2 3
> 3 5 3 4
>
>
> --
> efg
> Earl F. Glynn
> Bioinformatics
> Stowers Institute for Medical Research
>
> ______________________________________________
> 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

-- 
Department of Sociology
Fudan University,Shanghai
Blog:http://sociology.yculblog.com

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Received on Wed Jun 29 03:08:17 2005

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