R help - Apr 2011 - Convert a presence/ absence matrix to a list of presence only

this thread
(http://r.789695.n4.nabble.com/how-to-combine-presence-only-data-sets-to-one-presence-absence-table-td830140.html
) covered the need for making present list list to a matrix, 

Now, I ran into an opposite problem. I have a data matrix with 0, 1 on them,
what I need now is list of presence only for each column name

ie, this is what I have

        spl_A	spl_B	spl_C 
spcs1	1	1	0 
spcs2	1	0	1 
spcs3	0	1	1 


this is what I need

spl_A	  spl_B	spl_C 
spcs1  spcs1	spcs2 
spcs2	 spcs3	spcs3 



Thank you

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try this; added an extra row so that the lengths would not be even:
> x <- read.table(textConnection("       spl_A   spl_B   spl_C
+ spcs1   1       1       0
+ spcs2   1       0       1
+ spcs3   0       1       1
+ spcs4   0       0       1"), header = TRUE)
> closeAllConnections()
> x
      spl_A spl_B spl_C
spcs1     1     1     0
spcs2     1     0     1
spcs3     0     1     1
spcs4     0     0     1
>
> # get maximum in any column so we can pad out the lengths
> maxLen <- max(colSums(x))
>
>
> combine <- lapply(x, function(.col){
+     sp <- row.names(x)[.col == 1]
+     c(sp, rep("", maxLen - length(sp)))
+ })
>
> do.call(cbind, combine)
     spl_A   spl_B   spl_C
[1,] "spcs1" "spcs1" "spcs2"
[2,] "spcs2" "spcs3" "spcs3"
[3,] ""      ""     
"spcs4"
>

On Fri, Apr 22, 2011 at 2:10 PM, antu <ananta.acharya at gmail.com>
wrote:
> this thread
>
(http://r.789695.n4.nabble.com/how-to-combine-presence-only-data-sets-to-one-presence-absence-table-td830140.html
> ) covered the need for making present list list to a matrix,
>
> Now, I ran into an opposite problem. I have a data matrix with 0, 1 on
them,
> what I need now is list of presence only for each column name
>
> ie, this is what I have
>
> ? ? ? ?spl_A ? spl_B ? spl_C
> spcs1 ? 1 ? ? ? 1 ? ? ? 0
> spcs2 ? 1 ? ? ? 0 ? ? ? 1
> spcs3 ? 0 ? ? ? 1 ? ? ? 1
>
>
> this is what I need
>
> spl_A ? ? spl_B spl_C
> spcs1 ?spcs1 ? ?spcs2
> spcs2 ? ?spcs3 ?spcs3
>
>
>
> Thank you
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Convert-a-presence-absence-matrix-to-a-list-of-presence-only-tp3468479p3468479.html
> Sent from the R help mailing list archive at Nabble.com.
>
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?

Thank you, it perfectly worked, except I had to modify some codes on the
rep("", maxLen - length(sp)) because it gave me some error, thanks



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