Edited plotting file to cater for all the optimizers. Added a main fu…

[umarsajjad1992]

Purpose

Update the plotting file for optimization history to cater for all the optimizers in the current version

Description

• The plotting file only catered for SNOPT optimizer and would give errors when using SLSQP
• An issue was raised and a suggestion of a PR to correct this behavior
• Add a parser argument with opt option to check for optimizer and then run the code accordingly
• Added an if else statement to check which optimizer is being used
• The code would change the layout and number of the plots accordingly
• Added a try and except block to check whether an optimization history file exists or not

Expected time until merged

The PR is not urgent as, but a week should be enough for review and merging.

Type of change

What types of change is it?
Select the appropriate type(s) that describe this PR

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

run the code:

python plot_optHist.py --histFile output/opt.hst --outputDir output/ --opt "SNOPT"

try changing the --opt argument to either "SLSQP" or "IPOPT"

Checklist

• I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation

[marcomangano]

Thanks for opening this PR! Looking good, I was initially confused by the choice of a large try...except block but I see you are gracefully exiting at the end, makes sense.
I will shortly push a commit to fix the black and flake8 errors. @hajdik it looks like an ESP test is failing, can you check what is going on?

[ewu63]

I'm pretty sure the failure is just because we're running SNOPT tests and this is a PR submitted by an external contributor without access to that optimizer (hence this PR...ironically). May want to add skiptest or something similar to what we do with pyOptSparse tests.

[marcomangano]

I'm pretty sure the failure is just because we're running SNOPT tests and this is a PR submitted by an external contributor without access to that optimizer (hence this PR...ironically). May want to add skiptest or something similar to what we do with pyOptSparse tests.

You were right, the ESP test was missing the skiptest. Merging the PR once I verify that the tests pass.

[ewu63]

I generally prefer having all plt commands before any function definition, at the module level. Not blocking this PR though, since this is probably personal preference.