Getting Number of Nonzero Entries in the Constraints After Presolve in Julia
AnsweredHello Team,
I am a researcher working in economics and I have a question about obtaining specific model information under the Julia JuMP framework. Say that I have set up a generic linear program in Julia and the model has been optimized. I know that I can obtain the number of nonzero entries in the constraint before presolve using

Hi Henry,
I want to know if there is a way to obtain the number of nonzero entries in the constraint after presolve. I know the information can be retrieved from the log file, but I was wondering if there is a way to obtain the information programmatically without parsing the log file. This would really help with my research. Thanks!
There is currently no way to obtain the number of nonzeros after presolve has been performed. Currently, the only way to obtain this information is to parse the log output. This can be done via a MESSAGE callback.
Please note that the NumNZ attribute reports the number of all nonzeros in linear constraints and not the number of nonzeros in a specific constraint.
Best regards,
Jaromił0 
Thanks for the answer!
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