Adding Showalter Index to Thermo Functions

[michaelavs]

Description Of Changes

Adding a function to calculate the Showalter Index. Currently an individual file in the directory for testing purposes but will eventually be added to the "thermo.py" file when ready for approval/merging. Tested using dataset available in the GeoCAT-datafiles library and then by hand using guidelines for the function described by Galway on the visualization of the dataset in the GeoCAT-examples gallery.

Checklist

• Closes Add Showalter and Modified Showalter Index #630
• Tests added
• Fully documented

[CLAassistant]

All committers have signed the CLA.

[lgtm-com]

This pull request introduces 2 alerts when merging fc559c4 into 9ed0829 - view on LGTM.com

new alerts:

• 1 for Unused local variable
• 1 for Unused import

[dopplershift]

Thanks for the contribution @michaelavs ! Before delving into the details of the implementation, I have a design question. Right now the function is:

def showalter_index(pressure, temperature, lcl850, t500):

This requires the users to manually calculate the LCL from 850 hPa as well as pull out the environmental temperature. From your perspective as a user, would it be simpler to use to allow the user to only pass in the profile pressure and temperature and have the function do everything else:

def showalter_index(pressure, temperature):

? Or would that miss some use cases?

[michaelavs]

Thanks for the contribution @michaelavs ! Before delving into the details of the implementation, I have a design question. Right now the function is:

def showalter_index(pressure, temperature, lcl850, t500):

This requires the users to manually calculate the LCL from 850 hPa as well as pull out the environmental temperature. From your perspective as a user, would it be simpler to use to allow the user to only pass in the profile pressure and temperature and have the function do everything else:

def showalter_index(pressure, temperature):

? Or would that miss some use cases?

I don't see a reason to not narrow down the function to pass only profile pressure and temperature! I will be pushing a newer version here shortly with that change!

[lgtm-com]

This pull request introduces 1 alert when merging 3e39f67 into 3adfbd8 - view on LGTM.com

new alerts:

• 1 for Unused local variable

[lgtm-com]

This pull request introduces 1 alert when merging 3e39f67 into 1aaf805 - view on LGTM.com

new alerts:

• 1 for Unused local variable

[lgtm-com]

This pull request introduces 1 alert when merging cb5619e into 90e92c8 - view on LGTM.com

new alerts:

• 1 for Unused local variable

[lgtm-com]

This pull request introduces 1 alert when merging 9a21918 into 90e92c8 - view on LGTM.com

new alerts:

• 1 for Unused local variable

[lgtm-com]

This pull request introduces 1 alert when merging ea3c914 into 90e92c8 - view on LGTM.com

new alerts:

• 1 for Unused local variable

[dopplershift]

Thanks for the contribution! This is generally in pretty good, and thanks for including a test. I have a few comments to make things fit pep8 style better, plus a few clean-ups. Also, there are apparently some "blank" lines that have spaces--those seem to be angering the style checker.

[michaelavs]

@dopplershift
I went through and made the changes you requested. I believe all of the checks have passed that can pass without maintainer approval. In the mean time, I'll re-request your review on this one for when you are able to go over the changes again!

[dopplershift]

I can't believe it's been 4 weeks--time flies! This is looking good! Just a few things the style checker is complaining about. Also, can you add showalter_index to our list of functions in docs/_templates/overrides/metpy.calc.rst under "Soundings"? That way it will show up in the right table in our docs.

Thanks for working on this!

[dopplershift]

This is looking really good, thanks for sticking with us. One last thing: we have, internally MetPy banned the syntax like a * units.hPa because with arrays it can lead to hidden bugs when using masked arrays.

So while what you had wasn't in any way wrong, can you update to what I suggested to make the checker happy?

[dopplershift]

🎉 Just need the bots to pass and this will be in!

[dopplershift]

Congrats on your first contribution to MetPy @michaelavs !