Demetri Pananos

Demetri Pananos

Senior Data Scientist at Zapier. Part time PhD Candidate in Biostatsitics.

GSoC 2019: Testing an API

1 minute read

Published:

This is a really short update. Here are a couple things I have been working on since the last blog post.

1) Continuing to write the API so that it is intuitive

2) Writing unit tests

3) Benchmarking

When I last made a blog post about the API, users were to pass the ode parameters and initial conditions as a single vector. That was just to get things off the ground. Now that API is working, I can go back and make that a little more user friendly. The ODEModel (the meat and potatoes of the API) inherits from the theano.Op class, so in the make_node method I changed


    def make_node(self, x):
        x = theano.tensor.as_tensor_variable(x)

        return theano.Apply(self, [x], [x.type()])

to

    def make_node(self, odeparams, initial_condition):

        if np.ndim(odeparams)>1:
            odeparams = np.ravel(odeparams)
        if np.ndim(initial_condition) > 1:
            odeparams = np.ravel(initial_condition)


        odeparams = tt.as_tensor_variable(odeparams)
        initial_condition = tt.as_tensor_variable(initial_condition)
        x = tt.concatenate([odeparams,initial_condition])

        return theano.Apply(self, [x], [x.type()])

The little bit of logic at the beginning is to get around some shape problems with theano. So now to use the API, instead of doing

  all_params = pm.math.stack([<parameters here>, <initial conditions here>])
  forward = ode_model(all_params)

you can do


  forward = ode_model(odeparams = [<parameters here>], initial_condition = [<initial conditions here>])

which I think is much better. Explicit is better than implicit. This change actually makes some models run much faster which is interesting.

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An Interviewing Retrospective

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I’ve just recently accepted a new role as a data scientist at Zapier starting May 2022. This concludes a sequence of interviews on, what felt like, every other day. There’s a lot I learned in this experience, and I’d like to share some of that with you. I’m going to omit names of companies where needed, but I’ve tweeted enough for y’all to know who was in the mix for this role. At the end, I hope you learn something about yourself, your career, and interviewing.

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11 minute read

Published:

I’ve just recently accepted a new role as a data scientist at Zapier starting May 2022. This concludes a sequence of interviews on, what felt like, every other day. There’s a lot I learned in this experience, and I’d like to share some of that with you. I’m going to omit names of companies where needed, but I’ve tweeted enough for y’all to know who was in the mix for this role. At the end, I hope you learn something about yourself, your career, and interviewing.

New Year, New Me (Who This?)

3 minute read

Published:

I’m not usually the one to make resolutions, but this year is a little different for a few reasons. I’m working full time with no intent to chicken out and go back to academia (despite my constant threats to no one in particular to open a café), which means I have money for the first time in a long time as well as some unstructured free time. Because I turn 30 this year, I thought it would be prudent to make some resolutions so that I do not coast through the next decade of my life (a complaint I continually made in my 20s).