Decision Optimization

Decision Optimization

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  • 1.  Python doopl setStartingPoint for CPO interval variable

    Posted 06/11/20 08:51 AM
    Hello,
    I am trying to warmstart a CPOptimizer model with the value of an interval decision variable from python. 
    Is there a way to use setStartingPoint using the doopl interface? I do set_input for Tuples today. 
    I have searched the forum for prior posts on this topic but don't seem to find one. 
    Any help on this one is much appreciated!
    Thanks in advance,
    Bala

    ------------------------------
    Balakrishnan Ananthanarayanan
    ------------------------------

    #DecisionOptimization


  • 2.  RE: Python doopl setStartingPoint for CPO interval variable
    Best Answer

    Posted 06/11/20 01:00 PM
    Edited by System Admin 01/20/23 04:49 PM
    Hi,

    see example in OPL

    https://community.ibm.com/community/user/datascience/communities/community-home/digestviewer/viewthread?MessageKey=2e7e9b61-1183-48c9-be12-2dfd33e2ef09&CommunityKey=ab7de0fd-6f43-47a9-8261-33578a231bb7&tab=digestviewer#bm2e7e9b61-1183-48c9-be12-2dfd33e2ef09

    With doopl you can do the same

    if you write warmstartcposchedulingdoopl
    using CP;

tuple t
{
  int v;
}

{t} s=...;

{int} mySet={ i.v | i in s};

range r = 1..10;
dvar interval x[r] size 1;

dvar interval y[r] size 1;
// The following array of values (defined as data) will be used as  
// a starting solution to warm-start the CP Optimizer search.

int values[i in r] = (i in mySet)? 10 : 0;     

minimize sum( i in r ) startOf(x[i]) + sum( j in r ) startOf(y[j]);
subject to
{
ctSum: sum( i in r ) startOf(x[i]) >= 10;
forall( j in r ) ctEqual: startOf(y[j]) == j;
}   

execute
{
for(i in r) write(Opl.startOf(x[i])," ");
writeln();
}

tuple t2
{
  int a;
  int b;
}

{t2} result={<i,startOf(x[i])> | i in r};

execute
{
  result;
}

main
{
thisOplModel.generate();
var sol=new IloOplCPSolution();

for(var i=1;i<=10;i++) sol.setStart(thisOplModel.x[i],thisOplModel.values[i]);
cp.solve();
thisOplModel.postProcess();
cp.setStartingPoint(sol);
cp.solve();
thisOplModel.postProcess();
} ​

    then you can write the python file

    from doopl.factory import *

# Create an OPL model from a .mod file
with create_opl_model(model="warmstartcposchedulingdoopl.mod") as opl:
    # tuple can be a list of tuples, a pandas dataframe...
    s=[(5,),]
    opl.set_input("s",s )

    # Generate the problem and solve it.
    opl.run()

    # Get the names of post processing tables
    print("Table names are: "+ str(opl.output_table_names))

    # Get all the post processing tables as dataframes.
    for name, table in iteritems(opl.report):
        print("Table : " + name)
        for t in table.itertuples(index=False):
            print(t)​

    which will give you

    Table names are: ['result']
Table : result
Pandas(a=1, b=0)
Pandas(a=2, b=0)
Pandas(a=3, b=0)
Pandas(a=4, b=0)
Pandas(a=5, b=10)
Pandas(a=6, b=0)
Pandas(a=7, b=0)
Pandas(a=8, b=0)
Pandas(a=9, b=0)
Pandas(a=10, b=0)​


    regards



    ------------------------------
    ALEX FLEISCHER
    ------------------------------



  • 3.  RE: Python doopl setStartingPoint for CPO interval variable

    Posted 06/18/20 05:34 AM
    Thanks a lot Alex! This really helped!

    ------------------------------
    Balakrishnan Ananthanarayanan
    ------------------------------

    Original Message


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