[R] Creating subset using selected columns

[Rui Barradas]

Hello,

You could try something like the following.
The example below assumes your data.frame is named 'dat'


cnums <- grep("Peak\\.Area", colnames(dat))
subdat <- dat[cnums]

See ?regexp for the regular expressions used by ?grep.

Hope this helps,

Rui Barradas

Em 16-06-2013 08:20, Suparna Mitra escreveu:
> Hello R experts,
>   I need a help to create a subset file. I know with subset comand, its very
> easy to select many different columns, or threshold. But here I have a bit
> problem as in my data file is big. And I don't want to identify the column
> numbers
>
> or names manually. I am trying to find any way to automatise this.
>
> For example I have a file with about 1500 columns from TRFLP intensity
> data.
>
>
> And the column names are like:
>   [1] "Sample.Name"    "Marker"         "RE"             "Dye"
>   "Allele.1"       "Size.1"         "Height.1"       "Peak.Area.1"
>   "Data.Point.1"
>    [10] "Allele.2"       "Size.2"         "Height.2"       "Peak.Area.2"
>   "Data.Point.2"   "Allele.3"       "Size.3"         "Height.3"
> "Peak.Area.3"
>    [19] "Data.Point.3"   "Allele.4"       "Size.4"         "Height.4"
> "Peak.Area.4"    "Data.Point.4"   "Allele.5"       "Size.5"
> "Height.5"
>    [28] "Peak.Area.5"    "Data.Point.5"   "Allele.6"       "Size.6"
> "Height.6"       "Peak.Area.6"    "Data.Point.6"   "Allele.7"
> "Size.7"
>    [37] "Height.7"       "Peak.Area.7"    "Data.Point.7"   "Allele.8"
> "Size.8"         "Height.8"       "Peak.Area.8"    "Data.Point.8"
> "Allele.9"
>    [46] "Size.9"         "Height.9"       "Peak.Area.9"    "Data.Point.9"
> "Allele.10"      "Size.10"        "Height.10"      "Peak.Area.10"
> "Data.Point.10"
> .....
>
> Suppose I want to create a subset selecting all the columns with
> name Peak.Area
> (as in unix Peak.Area.*)
> How can I do that in R?
> Thanks a lot for the help.
> Best wishes,
> Mitra
>
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