Include functions for testing existence of derivatives. #10

[greebie]

This is a response to #10 that includes the following:

• Functions for accessing derivatives for graphml, gexf, and filtered text. (The latter has a placeholder only TextIO object until I figure out a logical way to process the zipped data).
• A function to test the existence of derivatives.
• Bool Vars TEXT, DOMAINS & NETWORK for easy checking.
• thing if TEXT else [] syntax to produce empty graphs instead of an error when no derivative exists.

To test:

I've been changing the filenames from 4867-fullurls.txt to NOT4867-fullurls.txt and then running the windows to see how it works. Then you just remove the NOT to restore the original.

[ruebot]

If there is a function that tests the existence of a derivative file, why aren't we displaying that error for the graphs? Just returning two giant empty graphs is going to confuse the user, especially when we do it silently. How about we just return the error that is setout in check_main?

[greebie]

I was trying to avoid wrapping the code in an if-else, because it seemed messy. I agree this is not the right approach. Let me try something else, like throw an error or something.

[greebie]

Upcoming commit uses a defined function and run_function() if TEXT else logging.error ('etc.') syntax instead. Might be a little more confusing for people not familiar with function definitions, but less messy than wrapping the commands in an if-else.

[greebie]

hmm. Cannot replicate this with my repo. Was this the "example" notebook or the plain and do you get the same problem with both?

[greebie]

Also, are you on 3.7 -- fstrings may not work if Python < 3.7.

[ianmilligan1]

I can update my Python to see if that matters, but since this worked before, it is possible to use something other than fstrings?

[ianmilligan1]

Yeah, there's a few other DH packages etc. that are still pegged to Python 3.5. Unless its absolutely mission critical, it'd be good to keep it working w/ earlier versions.

[greebie]

I can replace it, but the specs do say we require Python 3.7 or up. I can see the fstrings feature being useful for a project like this. It would be nice to keep it if we can.

Fstrings means we can create any variable and add the value to a string using {variable}. That means it can be very useful for madlibs-type work.

Also, it does not look like the error is fstrings-related. It's just that I cannot tell without being able to replicate.

[greebie]

I propose we look at getting this repo to work in 3.7, remove the extra notebook and then do another commit to revert to 3.5 support, even if that means moving to "string".format or something. I can just imagine watching dominos fall trying to accommodate 3.5 in this PR.

[greebie]

Had a change of mind. Switched to .format strings. If we want to support 3.5 we'll need to change the Docker settings.

[greebie]

Closing in favor of #40 .