Note to self: testing is really important

It's been an interesting couple of weeks. As I mentioned in my last blog post, I've been working on integrating WCSAxes into APLpy. It was going pretty well in the beginning but now things are starting to get complicated (just to be clear, I'm not complaining!). APLpy isn't a very big package but it still has a lot of features which I need to make sure work as I integrate WCSAxes into it. *THAT* is the tricky part. This means extensive testing after small re-writes of code to make sure new features work and I haven't broken something that was working previously. Well, that's the ideal workflow - I should have been doing extensive testing this way but sigh, I didn't. I've almost (I feel like the coyote who's *almost* caught the roadrunner as I say this) made most of the new code work but over the past few days I got so wrapped up in cleaning bits of code which I didn't test out fully that I broke a pretty important part of APLpy, plotting data cubes. I'm not sure where I broke it and my commit history is a mess (because I kept committing changes without testing them out fully again) so git bisect didn't help me identify where the problem started either.

This week is Eid, an Islamic holiday (Eid Mubarak to any Muslims reading this!!) so I won't have that much time to figure out where I introduced this bug, but once I do, I'll probably stock up on Pepsi, blare loud music in the background and carefully comb through my branch to examine all the code changes. That's it for now! :)

Weeks 7-8

I just counted and so far I have 14 merged pull requests which makes me really happy! Not all of them are huge PRs, a few of them are minor documentation changes but some of them took a bit more time to work on as I was implementing some new feature in WCSAxes or fixing some bug.

The latest thing I've been working on is integrating WCSAxes into APLpy. So APLpy is an Astropy affiliated package that also plots astronomical images and uses matplotlib for all the plotting tasks. My current task is to make changes to APLpy so that it uses WCSAxes to locate and plot all the ticks, labels, grids etc instead. So far things have been going pretty smoothly. Most of the functionality of APLpy is in place - there are a few small things here and there but I'm not too worried now that it's mostly working. Things have been going so smoothly in fact that I started to get a little bored with the work and consequently, my productivity decreased significantly.

Tom, my mentor, was at a conference this week so I haven't had a Hangout with him and discuss my latest work, which might also be why I haven't been very productive this week. I think my brain perceives our weekly Hangouts as deadlines where I have to report on my progress and that keeps me motivated. I like deadlines - there I said it! Well maybe having stressful deadlines all the time wouldn't be very pleasant but deadlines are kind of fun. They keep you focused and there's that edgy feeling you get close to the deadline 'can I finish this in time?!' Usually I just set my own personal deadlines like 'I have to get this thing done in two days, maximum four days' etc and that keeps me happy but like I said, I got a little bored.

Towards the end of the week, Tom said I could try implementing another feature in WCSAxes if I wanted so I decided to focus on that instead. Currently WCSAxes only plots major ticks but it would be useful if it could plot minor ticks as well.

(In case someone doesn't know about major and minor ticks from matplotlib, the red ticks are minor ticks and the black ones are major ticks. Also this is just an image produced with matplotlib, not WCSAxes)

This is a bit tricky because so far I haven't had to actually understand the math behind WCSAxes' calculations but now might be the right time to understand how it works. I currently have a very faulty implementation of minor ticks but it's fun to work on and hopefully I'll figure it out! :)

Weeks 5+6

You know that feeling when you think a task is going to be super hard but once you get to it, it turns out to be easier than you expected? And once you've finished it, you feel like you're the best programmer ever? I've been on that high for the past few days so I think I'll make a blog post while the feeling lasts.

Over the past two weeks or so I've been working on three tasks. The first thing I worked on was to implement different coordinate systems into WCSAxes. Previously, WCSAxes only allowed users to convert coordinates to the systems FK5 and Galactic but since there are a lot more coordinate systems out there, WCSAxes should be able to handle them. Like I said, this turned out to be pretty easy. The hardest part was probably refactoring the code to make it clean and efficient, but other than that I just had to use the Astropy method 'lookup_name' method to look up the correct coordinate class. Although, since this method is only available for Astropy 0.4, someone using WCSAxes with older versions of Astropy is limited to the old coordinate systems.

The second thing I worked on was a bug with the way axis labels were positioned on images. Previously, WCSAxes always tried to place axis labels as close as possible to the axis without intersecting with the tick labels.

but if the tick labels are in the way, it pushes the axis label further away

This could get annoying in certain situations and people preferred that axis labels always be positioned below the tick labels, whether or not they intersect. I had to read up on matplotlib's code to figure out how they position labels and tried to implement a similar way. It was a bit tricky since Matplotlib and WCSAxes handle ticks, labels and axes very different but luckily I was able to figure it out! And the results are

See? The axis label is now below the tick label by default! Users now also have the ability to adjust the padding of the axis label so they can move it as close or far away from the axis as they wish :)

The third thing that I've been working on is writing a wrapper for the package APLpy that uses WCSAxes. There are several packages out there that are used to plot astronomical images and one of them is APLpy, a package that my mentor helped write. The way APLpy does the actual plotting of images isn't all that great so we're trying to write a wrapper for it that uses WCSAxes to do the actual plotting, which will allow people to still use the package. So far work on the wrapper has been going good and I haven't hit any major roadblocks. Hopefully it'll continue to be this straightforward - or maybe not, things get interesting when they don't go the way you expected them to.

Now what I'm really excited about is the first release of WCSAxes! The package is almost ready for release except for one tiny feature I have to add. The sooner I finish this post, get to actual work and finish my task, the sooner we can do our first release!