Unsupported bound type "MI"

[flomnes]

Details for the issue

What did you do?

I called

pulp.LpProblem.fromMPS("problem.mps")

with this problem

problem.zip

What did you expect to see?

I expected the problem to be loaded without errors.

What did you see instead?

This error (output truncated)

    File "/home/runner/work/Antares_Simulator/Antares_Simulator/src/tests/cucumber/features/steps/common_steps/mps_utils.py", line 4, in load_problem
     return pulp.LpProblem.fromMPS(path)[1]
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/opt/hostedtoolcache/Python/3.12.12/x64/lib/python3.12/site-packages/pulp/pulp.py", line 1702, in fromMPS
     data = mpslp.readMPS(filename, sense=sense, dropConsNames=dropConsNames)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/opt/hostedtoolcache/Python/3.12.12/x64/lib/python3.12/site-packages/pulp/mps_lp.py", line 244, in readMPS
     readMPSSetBounds(line, variable_info)  # type: ignore[arg-type]
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   File "/opt/hostedtoolcache/Python/3.12.12/x64/lib/python3.12/site-packages/pulp/mps_lp.py", line 289, in readMPSSetBounds
     raise const.PulpError(f"Unknown bound {bound}")
 pulp.constants.PulpError: Unknown bound UI

Useful extra information

It looks like this line was added between 3.0.2 and 3.3.0

        else:
            raise const.PulpError(f"Unknown bound {bound}")

in the last nested if..else case, making fromMPS less tolerant to unknown bound types such as "UI".

According to this page, UI should be a valid bound qualifier

                 UI    integer variable   (0 <=) x <= b

What operating system are you using?

I have been able to reproduce in these environments

• Windows: ( _version: Windows Server 2022)
• Linux: ( _distro: Ubuntu 22.04)
• Mac OS: ( version: ___ )
• Other: ___

I'm using python version:

• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• Other: 3.12

I installed PuLP via:

• pypi (python -m pip install pulp)
• github (python -m pip install -U git+https://github.com/coin-or/pulp)
• Other: ___ (conda?)

Did you also

• Tried out the latest github version: https://github.com/coin-or/pulp
• Searched for an existing similar issue: https://github.com/coin-or/pulp/issues?utf8=%E2%9C%93&q=is%3Aissue%20

[dwr-zroy]

FYI, to fix #791, I added support for MI bounds in #792. A similar addition may be needed. I am not a maintainer of the library, so I might be wrong, but this is a potential pattern to follow for a fix.