[R] Combining values from a data.frame row with matrix rownames.

[Joshua Wiley]

Hi,

I believe you are looking for ?unlist.  Here is something that does
what I think you want with data that is my best guess at what yours is
like (if the data in seed_panel is stored as factor, you will probably
need to convert it first somehow).

> seed_panel <- data.frame(V2 = "507D22", V3 = "518F15", stringsAsFactors = FALSE)
> Control <- matrix(1:4, ncol = 2, dimnames = list(c("505E01", "etc"), c("Col1", "Col2")))
>
> unlist(c(seed_panel[1, ], rownames(Control)[1]))
      V2       V3
"507D22" "518F15" "505E01"

As a future suggestion, doing something like
dput(head(your_data_name)) is a simple way to provide us with the
first few rows of your data.

Cheers,

Josh

On Tue, Aug 17, 2010 at 10:36 AM, Gil Gamesh <gamesh.g at gmail.com> wrote:
> Apologies, I neglected to check that the email was plain text. Here is
> a the text of the previous email.
>
>
> Hello,
>
> I am trying to iteratively build a build a panel of variables to
> discriminate between two groups.
>
> My starting position is a matrix of experimental data and I have a function
> that will work through all pairs of variables and produce sensitivities,
> specificities and p-values for each pair and write it to a file (above
> particular cut-offs).
>
> I have a second function that will read that file in and use the pairs as a
> 'seed' adding a third variable from the original matrix and performing the
> same calculations and writing a new file.
>
> My aim is to iterate through this procedure five or six times.
>
> My difficulty is making the index vector to extract the values I need from
> the matrix of experimental data.
>
> The seed panel is a row in a data.frame:
>
> print(seed_panel[i,])
>
>      V2     V3
> 1 507D22 518F15
>
>
> and the variable to add to it is a rowname of the experimental matrix:
>
> print(rownames(Control[j,]))
>
> [1] "505E01"
>
> I haven't found a way to combine these three - I would like a vector
> c("507D22","518F15","505E01") - to subscript the matrix of experimental
> data.
>
> IndexList <- c(as.vector( seed_panel[ i, ], mode="any"), rownames( Control[
> j, ] ) )
>
> Gives:
>
> $V2
> [1] 507D22
> 18 Levels: 507D22 518F15 522C17 522K21 523A19 528H06 528P11 530H18 ...
> 585K18
>
> $V3
> [1] 518F15
> 20 Levels: 518F15 522C17 522K21 523A19 528H06 528P11 530H18 534L09 ...
> 590C18
>
> [[3]]
> [1] "505E01"
>
> and I haven't had any luck with variations on this that I've tried.
>
>
> Many thanks in advance for any help.
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/