Decision Optimization

Hi ,
I am using docplex.mp and trying to get the duals of a relaxed model.
I am trying to use the method get_duals(), however I am having trouble with the argument it needs.
So I have a model, mdl, and I relaxed it and called the new model mdl2. Now, I try to do the following:
c = mdl2.get_constraint_by_index(0)
mdl2.get_duals(cts), # edit : mdl2.get_duals(c)
however  I receive the  following error message:
TypeError: 'LinearConstraint' object is not iterable

Any ideas how to fix this?

best,​​
#DecisionOptimization

What is 'cts'? Is it a single constraint, a list of constraints, ...? It looks like you are calling a method that expects a list of constraints and you are passing a single constraint.

In any case, are you aware that a constraint object has a property `dual_value` which should return the dual value of that constraint? That might be an easier way to get that information.

------------------------------
Daniel Junglas
------------------------------

Original Message:
Sent: Thu June 18, 2020 04:44 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi ,
I am using docplex.mp and trying to get the duals of a relaxed model.
I am trying to use the method get_duals(), however I am having trouble with the argument it needs.
So I have a model, mdl, and I relaxed it and called the new model mdl2. Now, I try to do the following:
c = mdl2.get_constraint_by_index(0)
mdl2.get_duals(cts),
however  I receive the  following error message:
TypeError: 'LinearConstraint' object is not iterable

Any ideas how to fix this?

best,
#DecisionOptimization

Hi Daniel,

You are right. in my first post, I meant the following:
mdl2.get_duals(c)
Changing c to [c] gives the dual  as a list.
also c.dual_value do the trick.

Thanks for your help!
Is there a nicer way to get all the constraints from the relaxed model? rather than using get_constraint_by_index for each constraint?
best,



Original Message:
Sent: Thu June 18, 2020 04:50 AM
From: Daniel Junglas
Subject: use get_duals() / get_constraints_by_index docplex

What is 'cts'? Is it a single constraint, a list of constraints, ...? It looks like you are calling a method that expects a list of constraints and you are passing a single constraint.

In any case, are you aware that a constraint object has a property `dual_value` which should return the dual value of that constraint? That might be an easier way to get that information.

------------------------------
Daniel Junglas

Original Message:
Sent: Thu June 18, 2020 04:44 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi ,
I am using docplex.mp and trying to get the duals of a relaxed model.
I am trying to use the method get_duals(), however I am having trouble with the argument it needs.
So I have a model, mdl, and I relaxed it and called the new model mdl2. Now, I try to do the following:
c = mdl2.get_constraint_by_index(0)
mdl2.get_duals(cts),
however  I receive the  following error message:
TypeError: 'LinearConstraint' object is not iterable

Any ideas how to fix this?

best,
#DecisionOptimization

Hi,

Is there a nicer way to get all the constraints from the relaxed model? rather than using get_constraint_by_index for each constraint?

best,

------------------------------
s charaf
------------------------------

Original Message:
Sent: Thu June 18, 2020 05:01 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi Daniel,

You are right. in my first post, I meant the following:
mdl2.get_duals(c)
Changing c to [c] gives the dual  as a list.
also c.dual_value do the trick.

Thanks for your help!
Is there a nicer way to get all the constraints from the relaxed model? rather than using get_constraint_by_index for each constraint?
best,



Original Message:
Sent: Thu June 18, 2020 04:50 AM
From: Daniel Junglas
Subject: use get_duals() / get_constraints_by_index docplex

What is 'cts'? Is it a single constraint, a list of constraints, ...? It looks like you are calling a method that expects a list of constraints and you are passing a single constraint.

In any case, are you aware that a constraint object has a property `dual_value` which should return the dual value of that constraint? That might be an easier way to get that information.

------------------------------
Daniel Junglas

Original Message:
Sent: Thu June 18, 2020 04:44 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi ,
I am using docplex.mp and trying to get the duals of a relaxed model.
I am trying to use the method get_duals(), however I am having trouble with the argument it needs.
So I have a model, mdl, and I relaxed it and called the new model mdl2. Now, I try to do the following:
c = mdl2.get_constraint_by_index(0)
mdl2.get_duals(cts),
however  I receive the  following error message:
TypeError: 'LinearConstraint' object is not iterable

Any ideas how to fix this?

best,
#DecisionOptimization

In the documentation you can find that the Model class has member functions like  iter_range_constraints(), iter_binary_constraints(), iter_linear_constraints(), ...

Maybe this is what you are looking for?

------------------------------
Daniel Junglas
------------------------------

Original Message:
Sent: Thu June 18, 2020 06:08 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi,

Is there a nicer way to get all the constraints from the relaxed model? rather than using get_constraint_by_index for each constraint?

best,

------------------------------
s charaf

Original Message:
Sent: Thu June 18, 2020 05:01 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi Daniel,

You are right. in my first post, I meant the following:
mdl2.get_duals(c)
Changing c to [c] gives the dual  as a list.
also c.dual_value do the trick.

Thanks for your help!
Is there a nicer way to get all the constraints from the relaxed model? rather than using get_constraint_by_index for each constraint?
best,



Original Message:
Sent: Thu June 18, 2020 04:50 AM
From: Daniel Junglas
Subject: use get_duals() / get_constraints_by_index docplex

What is 'cts'? Is it a single constraint, a list of constraints, ...? It looks like you are calling a method that expects a list of constraints and you are passing a single constraint.

In any case, are you aware that a constraint object has a property `dual_value` which should return the dual value of that constraint? That might be an easier way to get that information.

------------------------------
Daniel Junglas

Original Message:
Sent: Thu June 18, 2020 04:44 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi ,
I am using docplex.mp and trying to get the duals of a relaxed model.
I am trying to use the method get_duals(), however I am having trouble with the argument it needs.
So I have a model, mdl, and I relaxed it and called the new model mdl2. Now, I try to do the following:
c = mdl2.get_constraint_by_index(0)
mdl2.get_duals(cts),
however  I receive the  following error message:
TypeError: 'LinearConstraint' object is not iterable

Any ideas how to fix this?

best,
#DecisionOptimization

Hi Daniel,
Yes that is what I was looking for! thank you !

best

------------------------------
s charaf
------------------------------

Original Message:
Sent: Thu June 18, 2020 08:37 AM
From: Daniel Junglas
Subject: use get_duals() / get_constraints_by_index docplex

In the documentation you can find that the Model class has member functions like  iter_range_constraints(), iter_binary_constraints(), iter_linear_constraints(), ...

Maybe this is what you are looking for?

------------------------------
Daniel Junglas

Original Message:
Sent: Thu June 18, 2020 06:08 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi,

Is there a nicer way to get all the constraints from the relaxed model? rather than using get_constraint_by_index for each constraint?

best,

------------------------------
s charaf

Original Message:
Sent: Thu June 18, 2020 05:01 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi Daniel,

You are right. in my first post, I meant the following:
mdl2.get_duals(c)
Changing c to [c] gives the dual  as a list.
also c.dual_value do the trick.

Thanks for your help!
Is there a nicer way to get all the constraints from the relaxed model? rather than using get_constraint_by_index for each constraint?
best,



Original Message:
Sent: Thu June 18, 2020 04:50 AM
From: Daniel Junglas
Subject: use get_duals() / get_constraints_by_index docplex

What is 'cts'? Is it a single constraint, a list of constraints, ...? It looks like you are calling a method that expects a list of constraints and you are passing a single constraint.

In any case, are you aware that a constraint object has a property `dual_value` which should return the dual value of that constraint? That might be an easier way to get that information.

------------------------------
Daniel Junglas

Original Message:
Sent: Thu June 18, 2020 04:44 AM
From: s charaf
Subject: use get_duals() / get_constraints_by_index docplex

Hi ,
I am using docplex.mp and trying to get the duals of a relaxed model.
I am trying to use the method get_duals(), however I am having trouble with the argument it needs.
So I have a model, mdl, and I relaxed it and called the new model mdl2. Now, I try to do the following:
c = mdl2.get_constraint_by_index(0)
mdl2.get_duals(cts),
however  I receive the  following error message:
TypeError: 'LinearConstraint' object is not iterable

Any ideas how to fix this?

best,
#DecisionOptimization