problem.setcbprenode
problem.setcbprenode |
Purpose
Set a user callback to be called during MISLP after the set-up of the SLP problem to be solved at a node, but before SLP optimization
Synopsis
problem.setcbprenode(callback, data)
feas = callback(prob, data)
Arguments
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prob
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The current SLP problem.
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callback
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The function to be called after the set-up of the SLP problem to be solved at a node.
callback returns an integer value. If the return value is nonzero, then further processing of the node will be terminated (it is declared infeasible).
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prob
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The problem passed to the callback function.
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data
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The user-defined object passed as
Object to
setcbprenode.
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feas
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feasibility flag. If
callback return a nonzero, the node is declared infeasible.
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Example
The following example sets up a callback function to be executed at each node before the SLP optimization starts. The array
IntList contains a list of integer variables, and the function prints the bounds on these variables.
IntList = [...] prob.setcbprenode(CBPreNode, IntList)
A suitable callback function might resemble the following:
def CBPreNode(myProb, intlist):
for i in intlist:
LO,UP = [],[]
myProb.getlb(LO,i,i);
myProb.getub(UP,i,i);
lb,ub = LO[0], UP[0]
if lb > 0 or ub < xp.infinity:
print("Col {0}: {1} <= {2}".format(i,lb,ub)
return 0
Further information
If a node can be identified as infeasible by the callback function, then the initial optimization at the current node is avoided, as well as further exploration of the node.
Related topics