[R] Restructuring data

[Daniel Malter]

Hi folks,

I am new to the list and relatively new to R. I am trying to unstack data
"arraywise" and could not find a convenient solution yet. I tried to find a
solution for the problem on help archives. I also tried to use the reshape
command in R and the reshape package but could not get result. I will
illustrate the case below, but the real dataset is quite large so that I
would appreciate an easy solution if there is any.

The current data structure (variable names): 

ID, TIME, BUY-A, BUY-B, SELL-A, SELL-B

Achieved structure (with the reshape command or the reshape package)

ID, TIME, BUY-A
ID, TIME, BUY-B
ID, TIME, SELL-A
ID, TIME, SELL-B 

This is regular unstacking with two identifier variables. Nothing special
though. What I am looking for and did not manage is the following structure:

ID, TIME, BUY-A, SELL-A
ID, TIME, BUY-B, SELL-B

I am quite sure it's pretty easy, but I could not find how to do this. 

Thanks a bunch,
Daniel