R help - Sep 2004 - erase columns

Can somebody remember me which is the command to erase
columns from a data frame?
Thanks Michele


		
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Hi, 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of michele lux
Sent: Dienstag, 14. September 2004 10:44
To: r-help at r-project.org
Subject: [R] erase columns

Can somebody remember me which is the command to erase
columns from a data frame?
Thanks Michele

I hope the following code-piece helps what you are looking for:

mydf <- as.data.frame(matrix(runif(100),ncol=5))

### if you want to erase the third column, do:
mydf <- mydf[,-3]


mydf2 <- as.data.frame(matrix(runif(100),ncol=20))

### if you want to erase the first, third and twentieth column, do:
mydf2 <- mydf2[,-c(1,5,20)]

Ciao,
Roland


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On 9/14/2004 at 10:44 AM michele lux wrote:
>>>Can somebody remember me which is the command to erase
>>>columns from a data frame?
>>>Thanks Michele
>>>
>>>
>>>		
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>>>
>>>http://it.seriea.fantasysports.yahoo.com/
>>>
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http://www.R-project.org/posting-guide.html


Dipl. bio-chem. Witold Eryk Wolski             @         MPI-Moleculare Genetic
Ihnestrasse 63-73 14195 Berlin                'v'    
tel: 0049-30-83875219                        /   \       
mail: witek96 at users.sourceforge.net        ---W-W----   
http://www.molgen.mpg.de/~wolski
      wolski at molgen.mpg.de

michele lux <nedluk <at> yahoo.it> writes:
> Can somebody remember me which is the command to erase
> columns from a data frame?
To delete a single column assign NULL to it.  That works
because a data frame is a list and that works for lists.
Here are three examples of deleting column 5, the Species 
column, from the iris data set:

   data(iris)
   iris[,5] <- NULL  

   data(iris)
   iris$Species <- NULL

   data(iris)
   iris[,"Species"] <- NULL