Update emissions.py with CO2 equivalent notation

[byersiiasa]

Added CO2-eq notation as this is currently used in our AR6 and other variable templates

[khaeru]

I suspect this may not work, because the underlying package, pint, interprets "-" as a minus sign. But let's see.

[codecov-commenter]

Codecov Report

Merging #36 (9245808) into main (00857b7) will not change coverage.
The diff coverage is 0.00%.

❗ Current head 9245808 differs from pull request most recent head 35f975a. Consider uploading reports for the commit 35f975a to get more accurate results

@@           Coverage Diff           @@
##             main      #36   +/-   ##
=======================================
  Coverage   73.10%   73.10%           
=======================================
  Files           4        4           
  Lines         145      145           
=======================================
  Hits          106      106           
  Misses         39       39           

Impacted Files	Coverage Δ
iam_units/emissions.py	100.00% <ø> (ø)
iam_units/update.py	0.00% <0.00%> (ø)

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[danielhuppmann]

Note that you edited a file that has as its first line "# DO NOT ALTER THIS FILE MANUALLY!"...

[khaeru]

Please expand the tests so that the new symbol you've added is tested:

units/iam_units/test_all.py

Lines 86 to 103 in 00857b7

	@pytest.mark.parametrize(
	"metric, species_in, species_out, expected_value",
	[
	("AR6GWP100", "CH4", "CO2", 27.9),
	("AR5CCFGWP100", "CH4", "CO2", 34),
	("AR5GWP100", "CH4", "CO2", 28),
	("AR5GWP100", "CH4", "CO2e", 28),
	("AR4GWP100", "CH4", "CO2", 25),
	("SARGWP100", "CH4", "CO2", 21),
	# Same-species conversion with metric=None and compatible names
	(None, "CO2", "CO2_eq", 1.0),
	(None, "CO2eq", "CO2e", 1.0),
	# Species names which are substrings of one another match correctly
	("AR5GWP100", "HFC143", "CO2", 328.0),
	("AR5GWP100", "HFC143a", "CO2", 4800.0),
	],
	)
	def test_convert_gwp(units, metric, species_in, species_out, expected_value):

[khaeru]

@danielhuppmann good eye! 😅

@byersiiasa you should instead modify the variable _EMI_EQUIV in the file update.py.

[byersiiasa]

Please expand the tests so that the new symbol you've added is tested:

units/iam_units/test_all.py

Lines 86 to 103 in 00857b7

	@pytest.mark.parametrize(
	"metric, species_in, species_out, expected_value",
	[
	("AR6GWP100", "CH4", "CO2", 27.9),
	("AR5CCFGWP100", "CH4", "CO2", 34),
	("AR5GWP100", "CH4", "CO2", 28),
	("AR5GWP100", "CH4", "CO2e", 28),
	("AR4GWP100", "CH4", "CO2", 25),
	("SARGWP100", "CH4", "CO2", 21),
	# Same-species conversion with metric=None and compatible names
	(None, "CO2", "CO2_eq", 1.0),
	(None, "CO2eq", "CO2e", 1.0),
	# Species names which are substrings of one another match correctly
	("AR5GWP100", "HFC143", "CO2", 328.0),
	("AR5GWP100", "HFC143a", "CO2", 4800.0),
	],
	)
	def test_convert_gwp(units, metric, species_in, species_out, expected_value):

@khaeru sorry not quite intuitive to me here, should I add:
(None, "CO2-eq", "CO2e", 1.0)
or other like (None, "CO2", "CO2-eq", 1.0)

Also - #L92
("AR5GWP100", "CH4", "CO2e", 28), should not have the e? or should all L89-94 be CO2e?

[khaeru]

Here are the relevant pytest docs: https://docs.pytest.org/en/stable/how-to/parametrize.html

To paraphrase, the 4 elements of that tuple get mapped to the function arguments named on L87, i.e. "species_in", "species_out", etc. Then you can see in the function body how those are used to call the tested function. Each line is an individual test case, so e.g.

• ("AR5GWP100", "CH4", "CO2", 28), tests that this particular conversion works,
• ("AR5GWP100", "CH4", "CO2e", 28), tests that "CO2e" is recognized as equivalent to "CO2" for a target ("species_out"), etc.

You could test "CO2-eq" as species_in and/or species_out, depending on how you expect that it should work!