Difference: SetsInAMPL (9 vs. 10)

Revision 102008-04-06 - MichaelOSullivan

Line: 1 to 1
 
META TOPICPARENT name="AMPLSyntax"
<-- Ready to Review - done - Lauren-->

Sets in AMPL

Line: 55 to 55
 Sets are usually defined in a data file:


Changed:
<
<
set NODES := Youngstown Pittsburgh Cincinnati 'Kansas City' Chicago Albany Houston Tempe Gary ;
>
>
set NODES := Youngstown Pittsburgh Cincinnati 'Kansas City' Chicago Albany Houston Tempe Gary ;
 

although they may be defined during declaration using either an explicit set literal or using a set expression:

Line: 252 to 253
 # The set of time-staged arcs set TIME_ARCS within TIME_NODES cross TIME_NODES := { (m, t) in TIME_NODES, (n, u) in TIME_NODES :
Changed:
<
<
( ( (m, n) in ARCS) and (t = u) ) or # The arcs used for transportation ( (m = n) and (ord(t, MONTHS) + 1 = ord(u, MONTHS)) )}; # The arcs used for storage
>
>
( ( (m, n) in ARCS) and (t = u) ) or # The transportation arcs ( (m = n) and (ord(t, MONTHS) + 1 = ord(u, MONTHS)) )}; # The storage arcs
 

to create TIME_ARCS you could use these statements

Line: 263 to 264
 set STORAGE_ARCS := union {t in MONTHS, (m, n) in ARCS : t <> last(MONTHS)} {(m, t, n, next(t, MONTHS)};
Changed:
<
<
set TIME_ARCS within TIME_NODES cross TIME_NODES := TRANSPORT_ARCS union STORAGE_ARCS;
>
>
set TIME_ARCS within TIME_NODES cross TIME_NODES := TRANSPORT_ARCS union STORAGE_ARCS;
 

Rather than looping over all possibilities and only keeping those that are appropriate, the new statement only loops over smaller sets that can be used to build up the TIME_NODES set efficiently.

 
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