On Mon, Jan 18, 2010 at 9:53 AM, Ivan Calandra <ivan.calandra@uni-hamburg.de
> wrote:

> Hi everybody!
>
> I'm working on R today so I have a lot of questions (you may have
> noticed that it's the 3rd email today). I'm new on R, so please excuse
> the "spam"!
>
> I have a dataset "ssfa" with many rows and the column names are:
>  > names(ssfa)
>  [1] "SPECSHOR"  "BONE"      "TO_POS"    "MEASUREM"  "FACETTE"   "SHEARFAC"
>  [7] "ENA_BA"    "SEL_FACET" "SEL_MEAS"  "Asfc"      "Smc"       "epLsar"
> [13] "HAsfc4"    "HAsfc9"    "HAsfc16"   "HAsfc25"   "HAsfc36"   "HAsfc49"
> [19] "HAsfc64"   "HAsfc81"   "HAsfc100"  "HAsfc121"  "Tfv"       "Ftfv"
>
> I want to aggregate that way:
> ssfamean <- aggregate(ssfa[c("Asfc", "Smc", "epLsar", "HAsfc4",
> "HAsfc9", "HAsfc16", "HAsfc25", "HAsfc36", "HAsfc49", "HAsfc64",
> "HAsfc81", "HAsfc100", "HAsfc121", "Tfv", "Ftfv")], ssfa[c("SPECSHOR",
> "BONE", "TO_POS", "FACETTE", "SHEARFAC", "ENA_BA")], mean).
>
> As you can see, it is very long since I have many variables. Basically I
> want to select all numerical variables (10 to 24), and all categorical
> variables except MEASUREM, SEL_FACET and SEL_MEAS without having to
> write each of them. I would also like to avoid writing the names, the
> indexes would be nice.
> I tried with:
>  > ssfamean <- aggregate(ssfa[c(ssfa[[10]]:ssfa[[24]])],
> ssfa[c("SPECSHOR", "BONE", "TO_POS", "FACETTE", "SHEARFAC", "ENA_BA")],
> mean)
> but it obviously doesn't work (well "obviously"...)
>

Numeric column indexing?

eg:
ssfa[10:24]
ssfa[[10:24]] #list including column name

col_index <- match("Asfc", ssfa)
total_num_cols <- 14
ssfa[col_index:total_num_cols]


I'm new at R also but that's how I would approach it.

Ben K.

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