[R] remove component from list or data frame

Erik Iverson iverson at biostat.wisc.edu
Thu Feb 8 19:31:18 CET 2007



Jason Horn wrote:
> Sorry to ask such a simple question, but I can't find the answer after 
> extensive searching the docs and the web.
> 
> How do you remove a component from a list?  For example say you have:
> 
> lst<-c(5,6,7,8,9)
> 
> How do you remove, for example, the third component in the list?

Is the object lst really a list?  Try is.list(lst) to check.
To remove an element from a vector, use for example, lst[-3]

> 
> lst[[3]]]<-NULL     generates an error:  "Error: more elements supplied 
> than there are to replace"
> 
> 

If lst were actually a list, that command would work with the obvious 
syntax fix.  So would lst[-3] though.

> 
> Also, how do you remove a row from a data frame?  For example, say you 
> have:
> 
> lst1<-c(1,2,3,4,5)
> lst2<-c(6,7,8,9,10)
> frame<-data.frame(lst1,lst2)
> 
> How do you remove, for example, the second row of frame?

You use

frame[-2, ] #remove second row, keep all columns.

> 
> Thanks,
> 
> - Jason
> 
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