Initializing help system before first use

problem.addcbprenode

Purpose
Declares a preprocess node callback function, called before the LP relaxation of a node has been optimized, so the solution at the node will not be available. This callback function will be called in addition to any callbacks already added by addcbprenode.
Synopsis

problem.addcbprenode(callback, data, priority)

nodinfeas = callback(my_prob, my_object)
Arguments
callback 
The callback function, which takes two arguments, my_prob, my_object and and returns an integer. This function is called before a node is reoptimized and the node may be made infeasible by returning 1 from the callback.
my_prob 
The problem passed to the callback function, callback.
my_object 
The user-defined object passed as data when setting up the callback with addcbprenode.
data 
A user-defined object to be passed to the callback function, callback.
priority 
An integer that determines the order in which multiple preprocess node callbacks will be invoked. The callback added with a higher priority will be called before a callback with a lower priority. Set to 0 if not required.
Example
The following example notifies the user before each node is processed: 
prob.addcbprenode(preNode, None, 0)
prob.mipoptimize("")
The callback function might resemble: 
def preNode(prob, object):

    return 0 # set to 1 if node is infeasible
Related topics
problem.removecbprenode, problem.addcbinfnode, problem.addcbintsol, problem.addcbnodecutoff, problem.addcboptnode.

Parent Topic Xpress problem methods

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