GSoC-Week6

The PR for NED is now merged and the ongoing PR right now is for IRSA. Details of this can be seen here. What still remains in this is to add an interface to ATLAS, which I described in my previous post.

Along with this I am also fiddling with the UKIDSS module that is right next on the refactoring TODO, though I am yet to make a PR for this yet.

One interesting titbit I had like to share is about editing commits that you have already pushed to Git.For instance say you committed some changes and then pushed these, but suddenly realized that you had forgotten to do a git add for some files that also went with the commit. Correcting this is very easy since the commit you would like to change is the last commit. First simply add whatever changes you wished had gone along with the commit. Now do:

git commit --amend

And all these changes will be added as a part of the commit as well. Now simply force push (git push -f )this commit back to Git

And lo! there will be a shiny new commit with all the changes as desired. Since GSoC is my first brush with Git, it feels very nice to discover neat facts like this!

Cheers till next week!

GSoC-Week5

Time flies! As this post marks the fifth(!) week of GSoC, I can't help feeling how true this (albeit hackneyed) saying is! So here goes the progress for this week:

This week resulted in one more PR with the NED web service. There are finishing touches to be added and docs to be done but apart from that the PR can now be seen here.

Since Astroquery is basically about querying web services, it involves writing methods to fetch various astronomical data such as spectra, images, astronomical references, etc. Most of these queries require similar arguments such as the object we are interested in querying, in addition to some query specific arguments that are relevant only to a particular kind of query. So what I had been doing is write a separate method for each of these queries. This led to quite some repetition also blowing up the code base. My mentor suggested that a better way to achieve the same thing would be to write a common method for all these queries, with optional keyword args that were relevant to specific query types. So for instance initially while I had

def get_positions(*args, **kwargs):
    # code

def get_diameters(*args, **kwargs):
    #code

...

after the refactor the effect was now similar to

def get_table(object_name, table='positions', **kwargs):
    #code

So now all the common arguments are abstracted out, and the optional specific to each query type just go into **kwargs. Amazingly this cut down the code by 455 sloc at the cost of adding 129 sloc. Awesome!. The specific commit pertaining to this is here

The next module coming up is IRSA. Of course most of this is tidying up converting functions to class methods, etc... Also we'll be adding an interface to the ATLAS service which is available under IRSA. This should add functionality to access several image services, apart from the NED images...

PS I am now using Syntax Highlighter for code snippets since gists may be troublesome for RSS readers.

GSoC - Week4

Hi! - I am a day late this time I guess. So this week I have mainly been finalizing Vizier. I have also worked on some code for the next module i.e. NED... though its a WIP and I am yet to make a PR.

Apart from this there were a couple of other auxilliary commits this week mainly to make work easy for the mainstream PRs. So there were PRs - #126, #127 and #128.

One very useful thing I learnt during these PRs was rebasing a git branch. Basically there were some conflicting commits and so the branch couldn't be automatically merged in the master. So I needed to rebase - resolve those conflicts and force update my PR's ( had to do this with two of the PRs!). I hadn't much familiarity with rebasing but astropy's documentation came out to be very handy. One interesting tool that I also learnt to work with is Meld. Meld is a visual tool that can give a huge helping hand in those 3 way merges - you have the local file, the remote file and the conflicting file that you must fix. With Meld all these files and the differences between them are visualized in one window - with simple clicks you can decide the diff you want to go with and lo presto you are done!

Another quite unrelated but very useful thing I found is that IPython has this lovely feature in which you can just feed in code with all the leading prompts(>>>) and (...) (for instance if you are copying from some docs, etc) and you don't need to do any editing, IPython understands that this is code meant to be executed. I realize (after reading this again) that I may not sound very obvious so read this up at the official IPython docs. It is a real time saver!

So Long :)

GSoC - Week3

So this week I have mainly been wrapping up Simbad as well as pushing in some preliminary code for VizieR. Both irsa_dust and Simbad are merged now. The PR for VizieR  is also up.

So the upcoming week should mainly involve completing Vizier and dealing with some more modules.

There's nothing much that I need to share this week - so this it for now!

UPDATE: Here are some working examples of Vizier in an IPython Notebook, browse them on nbviewer!