[R] How to transform the Matrix into the way I want it ???

[William Dunlap]

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Hongwei Dong
> Sent: Monday, November 09, 2009 2:24 PM
> To: R-help Forum
> Subject: [R] How to transform the Matrix into the way I want it ???
> 
> Hi, R users,
> 
> I'm trying to transform a matrix A into B (see below). Anyone 
> knows how to
> do it in R? Thanks.
> 
> Matrix A (zone to zone travel time)
> 
>  zone z1 z2 z3  z1 0 2.9 4.3  z2 2.9 0 2.5  z3 4.3 2.5 0
> 
> B:
> 
> from to time z1 z1 0 z1 z2 2.9 z1 z3 4.3 z2 z1 2.9 z2 z2 0 z2 
> z3 2.5 z3 z1
> 4.3 z3 z2 2.5 z3 z3 0

Try
   data.frame(From=rownames(A)[row(A)], To=colnames(A)[col(A)],
Time=as.vector(A))
You probably do not want a matrix because all of its elements
must have the same type, forcing Time to be character instead
of numeric.

E.g.,

> A<-rbind(Anacortes=c(Anacortes=0,Seattle=90,"Mount Vernon"=20),
+          Seattle=c(Anacortes=80, Seattle=0, "Mount Vernon"=60),
+          "Mount Vernon"=c(Anacortes=20,Seattle=70,"Mount Vernon"=0))
> data.frame(From=rownames(A)[row(A)], To=colnames(A)[col(A)],
Time=as.vector(A))
          From           To Time
1    Anacortes    Anacortes    0
2      Seattle    Anacortes   80
3 Mount Vernon    Anacortes   20
4    Anacortes      Seattle   90
5      Seattle      Seattle    0
6 Mount Vernon      Seattle   70
7    Anacortes Mount Vernon   20
8      Seattle Mount Vernon   60
9 Mount Vernon Mount Vernon    0

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com  

> 
> The real matrix I have is much larger, with more than 2000 
> zones. But I
> think it should be the same thing if I can transform A into B.
> 
> Thanks.
> 
> Garry
> 
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> 
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