[R] Could anyone help me reshape this "wide" data into "longitudinal" one? Thanks

[Frank Duan]

Dear R people,

I have a matrix like this:

      var1   var2    var3    var4 
a1   7.1   7.2       8.1    8.2 
a2  10.5  10.6    ...       ...
a3
b1
b2
b3
b4
c1
c2
...

The matrix row names are "a1", "a2", ......  and the matrix column
names are "var1", "var2", "var3" and "var4". Now I want to reshape
this data into a longitudinal-formatted one like this:


subject    seq   time    resp        
a              1      1        7.1
a              1      2        7.2
a              1      3        8.1
a              1      4        8.2
a              2      1       10.5 
a              2      2       10.6
a              2      3         ...
a              2      4         ...
a              3      1         ...
a              3      2
a              3      3
a              3      4
b              1      1
b              1      2
b              1      3
b              1      4
b              2      1
b              2      2
b              2      3
b              2      4
...             ...    ...
...             ...    ...
...             ...    ...


I always met errors when using "reshape" function. Could anyone give
me an idea how to do it?

Many thanks to you,

Frank