[R] how to extract the row names of a matrix using for loop or otherlooping

[ronggui]

lapply and rownames will do what you want

> class(t)
[1] "list"
> lapply(t,rownames)
[[1]]
[1] "ca" "cd"

[[2]]
[1] "cb"

[[3]]
[1] "cc"


======= 2005-12-11 01:17:47 ÄúÔÚÀ´ÐÅÖÐÐ´µÀ£º=======

>Hi all,
>  I have a matrix and its cluster...and i like to extract the row names of each cluster....but using the for loop or some other looping
>   
>  a<-matrix(c(seq(3,45,3),seq(10,6,-1)),4,5,byrow=F) 
> col<-c("ra","rb","rc","rd","re")
> rows<-c("ca","cb","cc","cd")
> dimnames(a)<-list(rows,col)  
>a                                ##        matrix
>  #-----------------------------------------------------------------------------------
>  #      ra rb rc rd re
>#  ca  3 15 27 39  9
>#  cb  6 18 30 42  8
>#  cc  9 21 33 45  7
>#  cd 12 24 36 10  6
>  ------------------------------------------------------------------------------------
>
>t<-list()                        ## clusters of the matrix
>  s<-list()
>  r<-c(1:3)
>   for(i in 1:3) 
>{ p<-seq(r[i],4,3)
> s[[i]]<-print(p)
>t[[i]]<-a[s[[i]],,drop=FALSE]
> }
>print(t)    
>  ----------------------------------------------------------------------
>  ##[[1]]
>   ra rb rc rd re
>ca  3 15 27 39  9
>cd 12 24 36 10  6
>  [[2]]
>   ra rb rc rd re
>cb  6 18 30 42  8
>  [[3]]
>   ra rb rc rd re
>cc  9 21 33 45  7
>----------------------------------------------------------------------------------------------------                                  
>   
>   
>  ##now if i want to extract the row names i can do it manually giving the values like
>   
>  rowc <- list(c(rownames(t[[1]])), c(rownames(t[[2]])), rownames(t[[3]]))
>   
>   
>  but i like to do using for loop or other loops...could you give me some suggestion..i´ve tried like this..but it is not working....
>   
>  rowc<-list(for(i in 1:3){p<-c();k<-rownames(t[[i]]);p[[i]]<-print(k)})
>   
>  ## here I´m getting only the final  rowname t[[3]]..other two values are missing..how could i do this to store all the values...........
>   
>  thank you...
>   
>  with regards,
>  eric.
>
>			
>---------------------------------
>
>
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>
>
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2005-12-11

------
Deparment of Sociology
Fudan University

My new mail addres is ronggui.huang at gmail.com
Blog:http://sociology.yculblog.com