In everything gloriously complex, it can be difficult to ascertain when you’ve reached a level of understanding that might merit debrief and reflection. In my forays into machine learning, this is probably as good a point as any.
I’ve been interested in Machine Learning for quite some time now. Since I first started stumbling on ImageNet and how it helped image processors classify images, to actual tinkering with an Alpha release of Google Vision, through the heady days of self-driving cars, and backing up even further, initial go’s at deriving meaning and topics from text with Python libraries like NLTK.
“Quite some time,” being relative. It’s a rapidly developing area of computer science, philosophy, mathematics, humanities, and their intersections.
Recently I’ve embarked on a project to try and derive topics from a corpus of academic articles in PDF form (around 700 of them), then by re-submitting one to the model, asking what other articles are “similar”. After quite a bit of trial and error, researching these emerging areas, and honing in on workflows that I might actually whiddle into working, I’m thrilled to have some results coming back that are – genuinly – spine-tingling.
The guts of this project falls on the python library, gensim. A masterful library meant to humanize the multi-dimensional math that underpins machine learning (and I use that term loosely here).
The rough sketch is thus:
- Point this little tool (called
atm, for “article topic modeling”, and the way it dispenses fun things to think about) at a dropbox folder with API credentials
- Downloads the entire directory, in this case, ~700 articles
- Create a bag of words for each document
- Strip of stopwords and punctuation (poorly at this point, I might add)
- Then the fun part: create a Latent Dirichlet Allocation (LDA) model with gensim
- Index ~100 topics that are suggested by this model, for this given corpus
- Finally, query the model with a document (in this case, an article from the corpus) for similarity to other documents in the corpus
The results are other documents in the corpus, and a percentile on topical vectors that match the article. I should stop myself here: the details are still forming, and while I’m getting a good grasp on relatively low-level how this works, that’s fodder for another post. At this point, the rough sketches.
Below are the results of a query, run through a Jupyter notebook of atm:
I submitted an article called
Arnold_2003.pdf, and it suggested a handful that match topically. The magic, the interest, lies in how these topics are derived and how the similarites are ranked. Much of this can be attributed to the LDA model that gensim creates for me. While these results are fascinating in their own right, what really sends chills down my spine, is the similarity with which this process / workflow shares with other domains like image processing, self-driving cars, speech recognition, etc.
Google’s Tensorflow has a wonderful tutorial, MNIST for ML that helped with my understanding. When the inputs you’re dealing with are 28x28 pixel images, of nothing but handwritten numerals from 0-9, you can begin to wrap your head around the math that supports machine learning. When we quantify input – sound, visual, text – into vectors and matrices, we can look for patterns over moving windows of input. Well, computers can. They can see patterns in a machine-digestable version of media we entertain with our senses. And when, with great grit and finesse, we can bubble up these patterns to more high-level libraries, we can apply them to actual corpuses. It’s phenomonal.
The results from atm are already encouraging, and it’s almost by-the-book tuning from tutorials. I want more corpuses, more targeted querying, adjusting of modeling parameters, the works. But for now, I’ve been thrilled to get something working with the tools I love and understand.
Much more to come on this front. An example: taking the thousands of PDFs that will soon flood our digital collections platform at Wayne State Digital Collections, run topic modeling on these, and provide new and interesting ways to find related documents.