On Nov 9, 2009, at 5:24 PM, Hongwei Dong wrote:
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
> ztz <- read.table(textConnection(" z1 z2 z3 \n z1 0 2.9 4.3 \n z2
2.9 0 2.5 \n z3 4.3 2.5 0"), header=T)
> ztz
z1 z2 z3
z1 0.0 2.9 4.3
z2 2.9 0.0 2.5
z3 4.3 2.5 0.0
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
Now taking some liberties with coercion:
> as.data.frame.table(ztz, responseName="Time")
Var1 Var2 Time
1 z1 z1 0.0
2 z2 z1 2.9
3 z3 z1 4.3
4 z1 z2 2.9
5 z2 z2 0.0
6 z3 z2 2.5
7 z1 z3 4.3
8 z2 z3 2.5
9 z3 z3 0.0
Or perhaps:
> data.frame(stack(as.data.frame(ztz)), From=colnames(ztz))
values ind From
1 0.0 z1 z1
2 2.9 z1 z2
3 4.3 z1 z3
4 2.9 z2 z1
5 0.0 z2 z2
6 2.5 z2 z3
7 4.3 z3 z1
8 2.5 z3 z2
9 0.0 z3 z3
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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