Weird incumbent behavior

回答済み

Lorenz Wagner

2024年03月27日 20:29

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Hello, I have the following problem. I am trying to evaluate the lowe bound and the incumbent via the log of my model and use the glt.get_dataframe() command to create a DataFrame. Unfortunately I get very strange results.

 Incumbent BestBd Gap ... LogNumber Seed Version
0 18.08 15.96 0.117257 ... 1 0 10.0.1
1 21.96 16.16 0.264117 ... 2 0 10.0.1
2 19.08 18.02 0.055556 ... 3 0 10.0.1
3 20.62 19.94 0.032978 ... 4 0 10.0.1
4 18.90 17.80 0.058201 ... 5 0 10.0.1
5 19.00 19.00 0.000000 ... 6 0 10.0.1
6 18.16 16.60 0.085903 ... 7 0 10.0.1

Normally the incumbent does not increase with a minimisation problem, but only decreases if it does. What could be the reason for this?

 

My model is structured something like this:

class Model:
    def __init__(self):
        self.model = Model()
    def variables(self):
        
    def constraints(self):
        
    def objective(self):
        
    def build(self):
        self.variables()
        self.constraints()
        self.objective()
        self.model.update()
        
m = Model()
m.build()
m.model.Params.LogFile = "./test.log"
m.model.optimize()

file='./test.log'
results, timeline = glt.get_dataframe([file], timelines=True)
default_run = timeline["nodelog"]
print(default_run)

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• 正式なコメント

  

  Simranjit Kaur

  • Gurobi Staff

  2026年11月13日 01:27

  This post is more than two years old. Some information may not be up to date. For current information, please check the Gurobi Documentation or Knowledge Base. If you need more help, please create a new post in the community forum, or try Gurobot, our chatbot interface offering instant, expert-level support.
• 

  Riley Clement

  • Gurobi Staff

  2024年03月27日 21:04

  Hi Lorenz,

  It looks like the LogNumber is increasing in that small dataframe snippet you show.

  I'm guessing you have multiple logs in the one file?  Note that Gurobi doesn't overwrite log files, it just appends to them.

  - Riley

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