[R] Extract names from vector according to their values

[Dennis Murphy]

Hi:

One more possibility:

> names(my.vector[grep('recommended', my.vector)])
 [1] "Matrix"     "boot"       "class"      "cluster"    "codetools"
 [6] "foreign"    "KernSmooth" "lattice"    "MASS"       "Matrix"
[11] "mgcv"       "nlme"       "nnet"       "rpart"      "spatial"
[16] "survival"
> names(my.vector[grep('base', my.vector)])
 [1] "base"      "compiler"  "datasets"  "graphics"  "grDevices" "grid"
 [7] "methods"   "splines"   "stats"     "stats4"    "tcltk"     "tools"
[13] "utils"

HTH,
Dennis

On Tue, Aug 2, 2011 at 11:21 AM, Sverre Stausland
<johnsen at fas.harvard.edu> wrote:
> Dear helpers,
>
> I can create a vector with the priority of the packages that came with
> R, like this:
>
>> installed.packages()[,"Priority"]->my.vector
>> my.vector
>         base          boot         class       cluster     codetools
>       "base" "recommended" "recommended" "recommended" "recommended"
>     compiler      datasets       foreign      graphics     grDevices
>       "base"        "base" "recommended"        "base"        "base"
>         grid    KernSmooth       lattice          MASS        Matrix
>       "base" "recommended" "recommended" "recommended" "recommended"
>      methods          mgcv          nlme          nnet         rpart
>       "base" "recommended" "recommended" "recommended" "recommended"
>      spatial       splines         stats        stats4      survival
> "recommended"        "base"        "base"        "base" "recommended"
>        tcltk         tools         utils
>       "base"        "base"        "base"
>
> How can I extract the names from this vector according to their
> priority? I.e. I want to create a vector from this with the names of
> the "base" packages, and another vector with the names of the
> "recommended" packages.
>
> Thank you
> Sverre
>
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