[R] extracting columns with same partial name

[Henrique Dallazuanna]

Try this:

DF[,grep("BOUTLENGTHTOT", l)]

On Thu, Jan 14, 2010 at 4:43 PM, Martin Striz <mstriz at gmail.com> wrote:
> Hi folks, I'm new to the list.
>
> I have a data file with 256 columns.  Here's just a subset of names(data):
>
>  [1] "MOUSE"               "BASEDATE1"           "PERCENTSLEEPTOT1"
>  [4] "PERCENTSLEEPNIGHT1"  "PERCENTSLEEPDAY1"    "BOUTLENGTHTOT1"
>  [7] "BOUTLENGTHNITE1"     "BOUTLENGTHDAY1"      "BOUTTHRESTOTP1"
>  [10] "BOUTTHRESHNITEP1"    "BOUTTHRESHDAYP1"     "BOUTTHRESTOTN1"
>  [13] "BOUTTHRESHNITEN1"    "BOUTTHRESHDAYN1"     "ACTONSET1"
>  [16] "PEAKACT1"            "BASEDATE2"           "PERCENTSLEEPTOT2"
>  [19] "PERCENTSLEEPNIGHT2"  "PERCENTSLEEPDAY2"    "BOUTLENGTHTOT2"
>  [22] "BOUTLENGTHNITE2"     "BOUTLENGTHDAY2"      "BOUTTHRESTOTP2"
>  [25] "BOUTTHRESHNITEP2"    "BOUTTHRESHDAYP2"     "BOUTTHRESTOTN2"
>  [28] "BOUTTHRESHNITEN2"    "BOUTTHRESHDAYN2"     "ACTONSET2"
>  [31] "PEAKACT2"            "BASEDATE3"           "PERCENTSLEEPTOT3"
>  [34] "PERCENTSLEEPNIGHT3"  "PERCENTSLEEPDAY3"    "BOUTLENGTHTOT3"
>
>
> You'll notice that certain names repeat, like BOUTLENGTHTOT1,
> BOUTLENGTHTOT2, etc.  These represent each day of data recording, and they
> go up to 17.
>
> I want to extract, for example, BOUTLENGTHTOT1 - 17.  I'm new to R, and the
> only ways that I know how to this are:
>
> newData <- data[, c("BOUTLENGTHTOT1", "BOUTLENGTHTOT2", ....)]
>
> or
>
> newData <- data.frame(col1 = data$BOUTLENGTHTOT1, col2 =
> data$BOUTLENGTHTOT2, .....)
>
> Both of which take a long time for 17 columns.  Is there a way that I can
> use a wildcard to grab all BOUTLENGTHTOT* columns?
>
> Thanks,
> Martin
>
>        [[alternative HTML version deleted]]
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O