Uh oh! Time for my occasional reminder post to use subset(), 
as in

subset(df, select = -z)

for this case.


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> Sent: 12 November 2003 12:51
> To: R-help list
> Subject: [R] column extraction by name ?
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> I have a data frame (df) with colums x, y and z.
> e.g.  df <- data.frame(x = sample(4), y = sample(4), z = sample(4))
> I can extract column z by: df$z or df[3]
> I can also extract columns x,y by: df[1:2] or by df[-3].
> 
> Is it possible to extract x,y columns in a "symbolic" fashion i.e.
> by equivalent of df[-z] (which is illegal) ???
> 
> Or alternativeley, is there an equivalent of "index" function,
> which would return index of the column given name ?
> 
> Ryszard
> 
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Simon Fear 
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