Douwe Osinga's Blog

Thursday, November 10, 2022

Neptyne: Making Spreadsheets Programmable

So yeah, it's been kinda quiet around here - famous last words on any blog, but I thought I should at least post something about what I've been up to here. Programmable Spreadsheets. Neptyne!

We tried this whole stealth mode thing. I'm not sure, maybe just developing out in the open is better. But here we are, we're ready to talk about what we are up to. 

After a bit over a 1000 pull requests, we’re ready to start showing a few things. So here it is, Neptyne: the programmable spreadsheet.

Neptyne Screenshot

So this is what it looks like. You have a spreadsheet on the left, a code pane on the upper right and down right a REPL. Write code in the code pane, use it directly from the spreadsheet and type commands into the REPL to try stuff. The code is all Python, but we've extended Python to be compatible with Excel.

So for example, you can just loop through a cell range with:

for row in A1:C10:
    for cell in row:
       if cell > 5:
           cell.set_background_color(255, 10, 10)

To make all cells with a value greater than 5 show up red.
Python screenhsot

Here's another example. We have a simple import function that fetches all the countries from the wikipedia that start with S, dump that into the spreadsheet by just assigning A1 to the results (it will spill over top create a table) and then we have a neat little function that annotates each row with the emoji flag. Finally we have a little widget that shows the countries on a map and shows the flags on mouse over. And all in less than 20 lines of code.

There's a lot more of neat stuff going on. Join the waitlist:

Friday, April 1, 2022

The Clever Bit and the Gold Rush

Gold bars (source: Wikimedia)


Saturday, March 19, 2022

What’s the clever bit?

I realized that the blog linked from my website is still pointing to the this old blogger thing while if I write something these days it is on medium. So I'm going to do some cross posting here to keep links from my website to medium until I come up with something better.

My last day at Sidewalk Labs, the company where I worked on making cities better for the last four years, was December 31st 2021. I’m going to do something new. It’s cool and exciting and I’ll write about it some other time.

Today I want to talk about the clever bit. If you ask me for advice about your startup, I’m going to ask you about the clever bit. What is your unique insight that nobody else thought of so far? It’s not enough to identify a problem to solve, you want to be able to solve it better than other people. Just having a clever bit is not enough of course — you do need to solve a problem for actual people, otherwise you just have a solution looking for a problem.

continue reading

Wednesday, May 10, 2017

Movie Recommendations

Today's project is a small Python notebook to recommend movies. I know, I know, there's a million of those out there, but this one is special, since it is not trained on user ratings, but on the outgoing links of the Wikipedia articles of the movies.

Why is that good? Two reasons. One is using diverse data. When you build a recommender system just on user ratings, you do get an Amazon-like system of people that liked this movie, also liked that movie. But if you're not using information like the year of the movie, the genre or the director, you are throwing away a lot of relevant features that are easy to get.

The second reason is that when you start a new project, you probably don't have enough user ratings to be able to recommend stuff from the get go. On the other hand, for many knowledge areas it is easy to extract the relevant wikipedia pages.

The outgoing links of a wikipedia page make for a good signature. Similar pages will often link to the same page. Estimating the similarity between two pages by calculating the jaccard distance would probably already work quite well. I went a little further and trained an embedding layer over the outgoing links.

The result is not Netflix quality, but it works reasonably well. As an extra bonus, I projected the resulting movies onto a 2 dimensional plane, rendering their movie posters as placeholders. It's fun to explore movies that way. Go play with it.

Wednesday, February 8, 2017

Amazon Dash and Philips Hue

When the Amazon Dash came out a few years ago, I thought it was an April Fool's joke. A button that you install somewhere in your house to order one specific product from Amazon? That's crazy!

It didn't take long for people to figure out how to use the button for something other than ordering products from Amazon. No higher hacking is required and at USD$ 4.99 a pop, quite affordable. When not in use, the button isn't connected to the wifi. So when you click it, the first thing it does is set up that connection. A script monitoring the local network can easily detect this event and then do something arbitrary - like order beer.

There are many hacks around, but none of them do exactly what I want:
  • When the last person leaves the house, all lights should switch off
  • When the first person comes back, all lights should switch back on
So I wrote a script that doesn't just monitor the Dash button, but also the presence of the phones of me and my wife on the local network. The basic rules are:
  • If any lights are on, switch them off when:
    • - the button was pressed
    • - no phones were seen on the network for 20 minutes
  • If any lights have been previously switched off, switch them on when:
    • - the button was pressed
    • - a phone is seen after 20 minutes of no phones
This way, the button can always be used to switch on or off the lights, but if you don't switch off the lights when leaving home, they will go off automatically. Unlike with a motion controlled set up, this won't happen if you are home but not moving (though it will happen if your phone runs out of battery). When you come home and you had previously switched off the lights using the button, they will come on automatically.

To get this working, check out the code, install the requirements and run: 

python auto_lights --hue_bridge=<bridge-ip> --phone_mac=<phone-macs> --dash_mac=<dash-mac>

While running, the program will also print any new mac addresses it detects and for extra convenience it also prints the manufacturer. You can use this to find out the mac address of your phone and of the dash button - switch your phone to airplane mode, wait for things to quiet down and when you switch airplane mode off, you should see your phone's mac address.

It works reasonably well. The longest I've seen my phone not contacting the wifi was 13 minutes, so 20 minutes seems safe. Coming home, it takes a little longer than ideal for the phone to reconnect to the wifi, but you can use the Dash button if you are in a hurry.

As always the code is on Github.

Thursday, January 26, 2017

Building a Reverse Image Search Engine using a Pretrained Image Classifier

In the Olden Days, say more than 10 years ago, building Image Search was really quite hard (see xkcd). In fact, when Alta Visa first came out with a search engine for images, they couldn't really do it. What they did was return the image that had text around it that most matched your query. It's a wonder that that worked at all, but it had to do for years and years.
Why we need Reverse Image Search: find more cat pictures (from: wikipedia)
How things have changed. These days Neural Networks have no problem detecting the actual content of pictures, in some categories outperforming their human masters. An interesting development here is reverse image search - supply a search engine with an image and it will tell you where else this or similar images occur on the web. Most articles on the web describing approaches on how to do this focus on things like Perceptual Hashing. While I am sure that is a good way, it struck me that there is a much simpler way.

Embeddings! Algorithms like Word2Vec train a neural network for a classification task, but they don't use the learned classification directly. Instead they use the layer just before the classification as a representation of the word. Similarly, we can use a pre-trained image classifier and run it on a collection of images, but rather than using the final layer to label the result, we get the layer before that and use that as a vector representation of the image. Similar images will have a similar vector representation. So finding similar images becomes just a nearest neighbor search.

As with a lot of things like this, getting the data to run the algorithm on is more work than getting the algorithm to run. Where do we get a set of representative images from? The images from the Wikipedia are a good start, but we might not want all of them. Most articles are about specific instances of things - for a reverse image search demo, classes of things are more interesting. We're interested in cats, not specific cats.

Luckily, Wikidata annotates its records with a 'is instance of' property. If you have imported a Wikidata snapshot into Postgres, then getting the wikipedia_ids for all values for the instance-of property is a simple SQL statement:
select properties->>'instance of' as thing, count(*) as c 
from wikidata group by thing

For some of these, Wikidata also provides us with a canonical image. For others we have to fetch the wikipedia page and parse the wikicode. We're just going to get the first image that appears on the page, nothing fancy. After an hour of crawling, we end up with a set of roughly 7 thousand images.

SkLearn provides us with an k-nearest-neighbor algorithm implementation and we're off to the races. We can spin-up a flask based server that accepts an image as a POST request, feeds that image into our pre-trained classifier. From that we'll get the vector representing that image. We then feed that vector into the nearest neighbor model and out fall the most similar images. You can see a working demo here

It mostly works well. If you feed it a cat, it will return pictures of cats, the definition of success on the Internet. On mobile, you can directly upload a picture from your phone's camera and that seems to go ok, too. The biggest limitation I've come across so far is that the algorithm is bad at estimating how good its guesses are. So if there aren't any suitable pictures in the training set, it will return the one that it thinks is the closest match, but to the human eye it seems fairly unrelated.

As always, you can find the code on Github.

Tuesday, January 17, 2017

Learning to Draw: Generating Icons and Hieroglyphs

In this blog post we'll explore techniques for machine drawn icons. We'll start with a brute force approach, before moving on to machine learning, where we'll teach a recurrent neural network to plot icons. Finally we'll use the same code to generate pseudo hieroglyphs by training the network on a set of hieroglyphs. With the addition of a little composition and a little coloring, we'll end up with this:

Last week's post "Deep Ink" explored how we can simulate computers playing with blobs of ink. But even if humans see things in these weird drawings, Neural Networks don't. If you take the output of Deep Ink and feed it back into something like Google's Inception, it offers no opinions.

The simplest thing I could come up with to generate icons was brute force. If you take a grid of 4x4 pixels, there are 2^16 possible black and white images. Feed all of them into an image classifier and see if anything gets labeled. It does. But 16 pixels don't offer a lot of space for expression, so the results are somewhat abstract if you want to be positive, or show weaknesses in the image classifier if you are negative. Here are some examples:

We can do a little better by going to 5x5. To give the model a little more to play with, we can add a permanent border. This will increase the size to 7x7, but we'll only flip the middle pixels. Unfortunately the amount of work we need to do going from 4x4 to 5x5 increases by a factor 512. Trying all 4x4 icons takes about an hour on my laptop. Exploring the 5x5 space takes weeks:

These are better and easier to understand. It some cases they even somewhat explain what the network was trying to see in the 4x4 images.

They say that if brute force doesn't work, you're just not using enough. In this case though, there might not be enough around. 8x8 for icons is tiny, but it would take my laptop something like 3 times the age of the universe to try all possibilities. Machine Learning to the rescue. Recurrent Networks are a popular choice to generate sequences, for example fake Shakespeare, recipes and Irish folk music, so why not icons?

I found a set of "free" icons at After deduping it'll give us about 4500 icons. Downsample them to 8x8 and we can easily encode them as sequences of pixels to be turned on. An RNN can learn to draw these quite quickly. Adding a little coloring for variety and on a 15x10 grid you'll get this sort of output:

These are pretty nice. They look like monsters from an 8 bit video game. The network learns a sense of blobbiness that matches the input icons. There's also a sense of symmetry and some learned dithering when just black and white doesn't cut it. In short it, learns the shapes you'll get when you downsample icons to 8x8.

As cute as these throw backs to the 80's are, 64 pixels still isn't a lot for an icon. Especially since the input isn't a stream of optimized 8x8 icons, but rather downsampled 32x32 icons (the lowest resolution that the icons8 pack comes in).

We can't use the same encoding for 32x32 icons though. With a training set of 4500, having a vocabulary of 64 for the 8x8 icons is OK. Each pixel will occur on average 70 times, so the network has a chance to learn how they relate to each other. On a 32x32 grid, we'd have a vocabulary of 1024 and so the average pixel would only be seen 4 times, which just isn't enough to learn from.

We could run length encode; rather than store the absolute position of the next black pixel, store its relationship with the previous one. This works, but it makes it hard for the network to keep track where it is in the icon. An encoding that is easier to learn specifies for each scanline which pixels are turned on, followed by a new line. This works better:

The network does seem to learn the basic shapes it sees and we recognize some common patterns like the document and the circle. I showed these to somebody and their first reaction was "are these hieroglyphs?" They do look like hieroglyphs a bit of course and it begs the question, what happens if we train on actual hieroglyphs?

As often with these sort of experiments, the hard thing is getting the data. Images of hieroglyphs on the Internet are found easily; getting them in nice 32x32 pixel bitmaps is a different story though. I ended up reverse engineering a seemingly abandoned icon rendering app for the Mac that I found on Google Code (itself abandoned by Google). This gave me a training set of 2500 hieroglyphs.

The renderer responsible for the image at the beginning of this post has some specific modifications to make it more hieroglyphy: Icons appear underneath each other, unless two subsequent icons fit next to each other. Also, if the middle pixel of an icon is not set and the area it belongs to doesn't connect to any of the sides, it gets filled with yellow - the Old Egyptians seem to have done this.

Alternatively we can run the image classifier over the produced hieroglyphs:

You can see it as mediocre labeling by a neural network that was trained for something else. Or as hieroglyphs from a alternate history where the Ancient Egyptians developed modern technology and needed hieroglyphs for "submarine", "digital clock" and "traffic light"

As always you can find the code on github.