Be specific about more indexes or values
State: closed

The generic "are not equal" really frustrated me just now when someone was conveying their issue.

This specific two errors lets me know which way around, although I believe having more indexes than data shows a place in the api for a default value (possibly per-index) which would allow this to later be reduced to the case I feel I fully understand of more data than indexes, which I think probably is unsolvable generally.

I can see that both have problems, but I still think it's more important to be specific about which side is mismatched.

- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry


Labels:
name: Error Reporting
description: Incorrect or improved errors from pandas

Comments:
Oh why not make specific errors instead of relying on value of error message... I'll patch it up at some point
i've pre-pended draft as I cannot find the button to make this a draft, which I was sure GitHub added to their old UI
Hello @Lewiscowles1986! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:









There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2020-07-14 16:05:47 UTC
funnily enough, getting the suite to compile and build on my windows laptop has been the largest hurdle. Lots of required C libraries to build and what borders on insane advice (copying executables & libraries to a magic path, rather than putting in path).

It's a rather large test suite which generates far too much noise to immediately fail or silence in a helpful way. `--pdb` and `-k` were essential to realize some flaws in my logic.

The makefile and `pip install -U -r requirements_dev.txt` fail, but I've eventually managed to get enough together to have the test-suite pass.
unsure if it needs a whatsnew entry. Technically I did add a new type of exception, but until I get a review (I'd like the suite to pass first), I've no idea. I'm guessing that there is code that relies on this behavior causing some of the environments to fail and not others.

I'll try rebasing now master is passing
Note for reviewer. I am happy of course squash the commits if you this is acceptable and required.
Now it's passing, I might like to suggest my initial wording may not have been as helpful as I'd have liked. I actually didn't understand the original message or surrounding code very well.

> Not enough values for column

and

> Too many values for column

Avoid the formatting, but improve readability from a case-study of 2 people (I could borrow a third).

I know naming and explaining is hard, but the cognitive load seems too high from the original, and I think these last suggestions could represent a clearer future desired-state. (For now I'm happy with the PR. It's less test wrangling, and at least stops me dropping to a debugger)
I've altered the commit message to be the same as the suggested change-log entry for 1.10 and squashed.
looks fine ex @mroeschke comment.
thanks @Lewiscowles1986 
Thanks all. Comms can be hard, so thank you all for your patience. @jreback @mroeschke 🚀