Datetime subtraction

[kylegilde]

Implements the DateTimeSubtraction class.

I don't know if the _more_tags method is needed. I copied and pasted it from CombineWithReferenceFeature.

[kylegilde]

looks like there is more work to do. I can see if I can keep working through the Code Contributor list of steps.

[kylegilde]

I think that I fixed all the type bugs, but maybe not in the most efficient manner.

[kylegilde]

I should be able to find some time this week/weekend to add some tests.

[solegalli]

Hi @kylegilde

I can't find your comment, so I paste it here:

**To summarize your proposal, you would like to see:

• variables_to_combine could accept the None argument and then select all datetime variables.
• reference_variables requires a list of datetime variables
• remove "var_a - var_a"
• allow "var_a - var_b and var_b - var_a" to occur

Is that correct?

Regarding the preventing of "var_a - var_b and var_b - var_a", it is debatable whether many people would like to see this functionality. I'm not sure that it would justify a separate class given that this functionality can be supported with a couple of lines of code.**

I am happy to add the extra code to prevent "var_a - var_b and var_b - var_a"

Thank you!

[kylegilde]

Hi @solegalli, I implemented the changes we discussed and started creating the test file. It's my first time using pytest, so I'm experiencing a learning curve.

[kylegilde]

Hi @solegalli , I haven't heard from you in a little while. If I make all of the requested changes and pass the tests, are you still interested in merging this code? Thanks

[solegalli]

Hi @solegalli , I haven't heard from you in a little while. If I make all of the requested changes and pass the tests, are you still interested in merging this code? Thanks

That would be great! Go for it.