R help - May 2008 - Data frame row manipulation

Greetings,

Q #1
------

How does one combine data frames by row ... no cleverness a la 
merge(), just add rows.

For example, given A with 20 rows and B with 30 rows, I want C = 
combine( A, B) having 50 rows.

Columns having matching names should be filled from both (all) 
sources with suitable coercion, unmatched would get NA in rows whose 
source does not have that column.


Q #2
------

Given data frame A having various columns including "vx".

I want to create a new data frame A2 that has 10 copies of each row 
in A, all the same as the source row except vx=seq(1:10).  The source 
row value of vx is overwritten.  A2 would have 10 times as many rows as A.

I have of course discarded idea of using of a for loop, but maybe 
that is what it takes.


TIA etc,

Chip Barnaby






---------------------------------------------------------
Chip Barnaby                   cbarnaby at wrightsoft.com
Vice President of Research
Wrightsoft Corp.               781-862-8719 x118 voice
131 Hartwell Ave               781-861-2058 fax
Lexington, MA 02421         www.wrightsoft.com

Hi Chip,

Try this:

# For Q1
R> C1 = rbind(A,B)

or

R> C2 = do.call(rbind,list(A,B))
R> all.equal(C1,C2)   # TRUE


# For Q2
R> set.seed(123)
R> vx=1:10
R> A = matrix(rnorm(500),ncol=10)
R> A2=t(sapply(A,rep,10))
R> A2[vx,]<- A[vx,]
R> A2
R> dim(A2)  # 500  10
R> dim(A)    # 50  10


HTH,

Jorge


On Fri, May 9, 2008 at 2:28 PM, Chip Barnaby <cbarnaby@wrightsoft.com>
wrote:
> Greetings,
>
> Q #1
> ------
>
> How does one combine data frames by row ... no cleverness a la merge(),
> just add rows.
>
> For example, given A with 20 rows and B with 30 rows, I want C = combine(
> A, B) having 50 rows.
>
> Columns having matching names should be filled from both (all) sources with
> suitable coercion, unmatched would get NA in rows whose source does not
have
> that column.
>
>
> Q #2
> ------
>
> Given data frame A having various columns including "vx".
>
> I want to create a new data frame A2 that has 10 copies of each row in A,
> all the same as the source row except vx=seq(1:10).  The source row value
of
> vx is overwritten.  A2 would have 10 times as many rows as A.
>
> I have of course discarded idea of using of a for loop, but maybe that is
> what it takes.
>
>
> TIA etc,
>
> Chip Barnaby
>
>
>
>
>
>
> ---------------------------------------------------------
> Chip Barnaby                   cbarnaby@wrightsoft.com
> Vice President of Research
> Wrightsoft Corp.               781-862-8719 x118 voice
> 131 Hartwell Ave               781-861-2058 fax
> Lexington, MA 02421         www.wrightsoft.com
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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