PR for getting pixel_edges along with pixel_values in axis_world_coords

[yashrsharma44]

This PR adds a new functionality for returning pixel_edges along with pixel_values from axis_world_coords.
Things to TODO:

• Add tests
• Documentation
• Add changelog

Ping @DanRyanIrish @Cadair

Fixes part of the stagnant PR #172

[ghost]

Thanks for the pull request @yashrsharma44! Everything looks great!

[pep8speaks]

Hello @yashrsharma44! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

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

Comment last updated at 2019-05-23 14:06:40 UTC

[DanRyanIrish]

Hi @yashrsharma44. This looks good. I left a couple minor formatting comments and then assuming this passing the online tests, I think it's ready to approve.

[yashrsharma44]

Let me add some tests for the helper functions.

[yashrsharma44]

Hey @DanRyanIrish , do we need to mention about this new feature in the docs, or shall this go unnoticed?

[DanRyanIrish]

I think this would be great to add this to the docs. It may be a very useful feature for users. It doesn't have to be too long. Just a couple sentences at the end of the Coordinate Transformation section saying some like:
"By default ~ndcube.NDCube.axis_world_coords returns the coordinates at the center of each pixel. However, the pixel edges can be obtained by setting the edges kwarg to True."
Then provide an example showing the output:

>>> my_cube.axis_world_coords(edges=True)
output...

[DanRyanIrish]

The tests are failing because there are some blank lines containing spaces:
ndcube/ndcube.py:329:1: W293 blank line contains whitespace
ndcube/utils/cube.py:164:1: W293 blank line contains whitespace
ndcube/utils/cube.py:169:1: W293 blank line contains whitespace
ndcube/utils/cube.py:173:1: W293 blank line contains whitespace
ndcube/utils/cube.py:188:1: W293 blank line contains whitespace

[yashrsharma44]

The blank spaces that I added between the docstrings are creating the pep8 issue

[DanRyanIrish]

Right. But it's not that the lines exist. It's that they contain spaces. You just need to delete those spaces without removing the empty line and that should fix it.

[yashrsharma44]

Sure, I would make those changes.

[DanRyanIrish]

Great work @yashrsharma44