UDFs that filter on url should also filter on src

[ruebot]

We are currently unable to run a number of DataFrame filters on .imageLinks() and webgraph() because they have src and/or dest columns instead of url. The DataFrame filters should be able to filter on those columns as well.

• keepUrlsDF
• keepDomainsDF
• discardUrlsDF
• discardDomainsDF
• discardUrlPatternsDF
• keepUrlPatternsDF

[ruebot]

@SinghGursimran want this one since we're stuck in a holding pattern on the Python side of things until I sort out the Scala UDF -> Python UDF linkage?

[SinghGursimran]

@ruebot Shall I add a new function to incorporate src and dest OR accommodate this within the same function using an extra argument?
Amending the current function would require a change in docs as well...

[ruebot]

Based on the chat @lintool and I where having in Slack this morning, it'd be amending the current functions. I think we could just do this with try cases (oh, I don't know what the proper Scala term is for it 😆 ) for url and src. I don't think we need to do dest or image_url, though @ianmilligan1 might have a use case for that. How's that sound?

[SinghGursimran]

Ok....

[ruebot]

@SinghGursimran If it helps to see an actual use case/test case, this is how it popped up: https://gist.github.com/ruebot/60b5f848252284b7f380e3d5006d7135

I tried to run the .imagegraph() version of the script over the weekend only to realize I couldn't do it 🤦‍♂️