New GAMS solver interface, writer, and solution loader. #3683

AnhTran01 · 2025-08-07T18:07:31Z

Fixes NA

Summary/Motivation:

This PR introduced a new GAMS solver interface that uses the LinearRepnVisitor to enable coefficient gathering when writing out the scalar GAMS model in gms format.

Changes proposed in this PR:

New GAMS solver interface in pyomo.contrib.solver.solvers
New GAMS writer in pyomo.repn.plugins
New GAMS solution loader in pyomo.contrib.solver.solvers

Legal Acknowledgement

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I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

…ittest and coverage test

AnhTran01 · 2025-08-07T18:07:57Z

@boxblox
@abhosekar

mrmundt · 2025-08-07T18:11:30Z

@AnhTran01 - Please make sure to run black on your changes!

mrmundt

Immediate piece of feedback, recognizing that I have not thoroughly looked over anything - there are no tests anywhere, and there absolutely will need to be some.

Thanks for this, though, I am so excited!!

…riting process. Added WIP unittest for the new solver interface

…ion error

… and writing to gms.

pyomo/repn/plugins/gams_writer_v2.py

… constraint). Fixed bug of load_solution that contains constraint id in addition to variable id

…e_gdx_results

…arsing solver_options

jsiirola

(Some initial comments, mostly on configuration)

pyomo/contrib/solver/solvers/gams.py

jsiirola · 2025-08-15T21:42:22Z

pyomo/contrib/solver/solvers/gams.py

+        if config.logfile is not None:
+            config.logfile = os.path.abspath(config.logfile)
+
+        config.writer_config.put_results_format = 'gdx' if gdxcc_available else 'dat'


This should probably only overwrite the configuration if it is still None (that way users can set / override the interface)

…lable() and version()

…are no longer valid.

pyomo/contrib/solver/solvers/gams.py

pyomo/repn/plugins/gams_writer_v2.py

pyomo/contrib/solver/solvers/gms_sol_reader.py

blnicho · 2025-11-18T20:03:46Z

@AnhTran01 did you see the review comments from @mrmundt? Are you going to have a chance to work on this in the near future?

AnhTran01 · 2025-11-18T20:08:34Z

@blnicho I've seen the comments and they're part of my todo. I'm aiming to implement these by Nov. 30th.

…bounds - default to large number

…fied handling log_level conditional.

…ib.solver.common.util

…rsion. Added helper function for _simple_model and _run_simple_model

…write_path_win8p3

… -INF when None is provided

…nd _run_simple_model

Co-authored-by: Miranda Mundt <[email protected]>

Added new GAMS solver interface, writer, and solution loader. WIP: un…

1177492

…ittest and coverage test

Norman_Tran and others added 2 commits August 7, 2025 14:14

Ran black -S -C on commited files

2385654

Typo!

b36086f

mrmundt requested changes Aug 7, 2025

View reviewed changes

Norman_Tran and others added 14 commits August 7, 2025 17:02

Added ignore checking for constant in the objective function during w…

e91e480

…riting process. Added WIP unittest for the new solver interface

Added support for add_options for multiple solver_options

b060096

typo

96ba646

ran black formatter

b0f16a3

added add_options in the solver_interface

dde656c

Fixed bug with unable to create tmpdir. Updated test_gams_v2.py

3476f72

Merge branch 'main' into GAMS_new_solver_interface

ddfd98c

Added handling single bounded variable case (None,#) or (#, None)

eb0a3db

Match solver interface and writer configs to prevent implicit definit…

c6d2d01

…ion error

Added new gams solver interface for test_all_solvers_list()

2a6dcb7

Fixed bug of handling valid ub when writing pyomo expression

b6ead27

Fixed bug when using ComponentMap to extract duals in gms_sol_reader.py

89f80e0

Corrected handling of solution_loader. Implemented bounded constraint…

b0c3450

… and writing to gms.

Added offdigit based on error log message suggestion

a9df1d7

boxblox reviewed Aug 14, 2025

View reviewed changes

pyomo/repn/plugins/gams_writer_v2.py Show resolved Hide resolved

mrmundt and others added 4 commits August 15, 2025 07:47

Merge branch 'main' into GAMS_new_solver_interface

e04c89f

Fixed bug of extracting constraint dual when alias exits (for bounded…

518758e

… constraint). Fixed bug of load_solution that contains constraint id in addition to variable id

Added aliases as part of parse_dat_results to be consistent with pars…

a2ef9cc

…e_gdx_results

Removed code duplication between the solver interface and writer by p…

c33095d

…arsing solver_options

jsiirola reviewed Aug 18, 2025

View reviewed changes

Norman_Tran and others added 4 commits August 19, 2025 14:31

Revised code based on John's review. WIP: Handling rehash within avai…

f609ca2

…lable() and version()

Re-added config into available and version, and deprecated test that …

ec5aa6a

…are no longer valid.

Merge branch 'main' into GAMS_new_solver_interface

e760a1c

Sanity check config.writer_config.put_results_format without setdefault

7bb817b

mrmundt requested changes Sep 9, 2025

View reviewed changes

blnicho added this to Pyomo 6.10 Nov 11, 2025

github-project-automation bot moved this to Todo in Pyomo 6.10 Nov 11, 2025

blnicho moved this from Todo to Review In Progress in Pyomo 6.10 Nov 11, 2025

Norman_Tran and others added 18 commits January 6, 2026 09:47

Corrected typos and added handling case for integer variable without …

58362af

…bounds - default to large number

Removed duplicate config within solver and writer (row_order). Simpli…

94396a9

…fied handling log_level conditional.

Removed duplicate error message string that is handled by pyomo.contr…

6243b06

…ib.solver.common.util

Renamed to test_gams.py and added cache unittest for available and ve…

afa0ef0

…rsion. Added helper function for _simple_model and _run_simple_model

Removed deprecated functions (_simple_model / _run_simple_model / _re…

a723a06

…write_path_win8p3

Updated the handling of bounds for integer variables by using INF and…

bf8db4f

… -INF when None is provided

Added document_class_CONFIG to remove redundant documentation

71a35e8

Additional documentation cleanup

d619cb3

Updated test_gams.py comments for standalone function _simple_model a…

437a03a

…nd _run_simple_model

Moved gams_results in postsolve into results.extra_info

f1b9b03

Merge branch 'main' into GAMS_new_solver_interface

c677f71

ran black formatter

f845c0c

Merge branch 'main' into GAMS_new_solver_interface

c44577d

fixup of writing bounds

a92d26b

Merge branch 'main' into GAMS_new_solver_interface

bc8bca3

black 26.1.0 formatting

8ebf3a0

Added results.solver_config in gams.py:solve

2f13aeb

keep solver_log in results object

0f4cba1

boxblox mentioned this pull request Jan 21, 2026

Add flexibility into error message checking on gurobi_minlp #3822

Merged

boxblox and others added 5 commits January 21, 2026 16:19

Merge branch 'main' into GAMS_new_solver_interface

225744d

Apply suggestion from @mrmundt

3c504ea

Co-authored-by: Miranda Mundt <[email protected]>

Apply suggestion from @mrmundt

331a367

Co-authored-by: Miranda Mundt <[email protected]>

fixups

0e0c637

Merge branch 'main' into GAMS_new_solver_interface

08c63e7

New GAMS solver interface, writer, and solution loader. #3683

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New GAMS solver interface, writer, and solution loader. #3683

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AnhTran01 commented Aug 7, 2025

Fixes NA

Summary/Motivation:

Changes proposed in this PR:

Legal Acknowledgement

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AnhTran01 commented Aug 7, 2025

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mrmundt commented Aug 7, 2025

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blnicho commented Nov 18, 2025

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AnhTran01 commented Nov 18, 2025

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