lang-en on Luis’ Corner

Recording cell execution time in Jupyter notebooks

Tue, 19 May 2026 12:04:07 -0500

The jupyterlab-execute-time extension for Jupyter Lab records the time it has taken / took to execute a cell.

It was developed by the D. E. Shaw group (never heard of them), so one can be reasonably sure it has been tested to some extent.

Week 13: Software engineering in scientific projects

Mon, 13 Apr 2026 19:53:36 -0500

Note: Week 13 covers April 13 through 19 of 2026

On the data science project

Defining dependencies aka software engineering

As I’ve mentioned before, I’m working on the side on a computer vision project. The previous work was more of a proof-of-concept, rather than a complete software solution. As such, I, who happen to know a thing or two about software engineering, thought it best to start by adding the explicit list of dependencies needed to run the project. Since I’m bored of always using the pip package manager, with the usual requirements.txt file, I opted instead for the hot stuff: the uv package manager.

Modifying a PDF in Zotero and keeping the annotations

Mon, 13 Apr 2026 00:00:00 +0000

What this post is about

In this post, I will explain my workflow for modifying a PDF stored as a file in a Zotero library while keeping the annotations. Could this be better? Quite possibly. This is just the way I do it.

Some context (just like recipe websites?)

A document I’ve been reading is neither OCR’ed nor has a table of contents (ToC). This book, reaching almost 600 pages, has been particularly fastidious to navigate around. I remember how I had the same issue with a physics textbook PDF I had in 2024, and how I used JPdfBookmarks to add the ToC myself. I wondered if it’d be possible to update the PDF that was uploaded to a group library and get to keep the annotations. This short post explains how to do so.

Week 12: Ramsey theory, Crane et al.’s heat method

Mon, 06 Apr 2026 16:25:14 -0500

Note: Week 12 covers April 6 through 12 of 2026

Ramsey theory

A few months ago, I watched N Is a Number: A Portrait of Paul Erdős, a documentary on late Hungarian mathematician Paul Erdős. During a discussion of the party puzzle and Ramsey theory, an article co-authored by Ronald L. Graham came up. I figured they were referring to this July 1990 Scientific American Magazine article¹. I hadn’t read it in its entirety, even though I downloaded it in October/November 2025.

Disabling the Firefox full-screen animation and popup

Thu, 02 Apr 2026 17:32:03 -0500

Note: I’m using Firefox 149.

To disable the full-screen animation and popup that get triggered when you press F11, which I personally found annoying, do the following:

Type about:config in the address bar and press Enter to open the advanced config window.
It will, most likely, prompt you for confirmation before going ahead. Click “Accept the Risk and Continue”.
Type full-screen-api in the search bar to filter the options.
And perform the following changes:

Week 10: Circling back

Thu, 02 Apr 2026 13:24:36 -0500

Note: Week 10 covers March 23 through 29 of 2026

Image segmentation

I’m working on a side project related to the problem of image segmentation. There’s a working implementation of OpenCV subroutines that manages a decent result, but we’re looking into ways to improve it. Besides computer vision, I will have to deepen my knowledge of statistics, as we plan on comparing the real distribution of the objects, measured with a callipers, with the computed one.

From an old 2021 blog I forgot all about

Sat, 28 Mar 2026 00:00:00 +0000

What is this?

I tried to start blogging in 2021, I was in high school at the time, but never got too far (didn’t know what to post, or was too shy).

The GitHub repo description I had at the time:

Personal GitHub website of Luis Torres. I’m not even in uni yet. So I write about cool things for my friends ✈️

(I never shared it with my friends…)

The Odyssey: Some pointers

Sat, 28 Mar 2026 00:00:00 +0000

Some links I collected while reading Homer’s Odyssey during the 2025-1 semester:

Reference

Odyssey - Wikipedia entry (English)

Quite comprehensive at times. Basic reference for me.
Smith - Dictionary of Greek and Roman biography and mythology [Wikipedia]

Useful when you don’t know why someone is important.
Map: ACHAEANS and TROJANS - Greek Mythology Link

The geography might not be as relevant, but it helped me understand the kind of terrain that Odysseus was facing.

Tango trees in Computer Science

Wed, 25 Mar 2026 15:48:18 -0500

I was reading about specialized variants of Dijkstra’s algorithm when I saw the name Van Emde Boas and it grabbed my interest.

I skimmed that page and saw another article in the “See also” section: Tango tree.

A tango tree is a type of binary search tree proposed by Erik D. Demaine, Dion Harmon, John Iacono, and Mihai Pătrașcu in 2004.[1]

As for its etymology:

It is named after Buenos Aires, of which the tango is emblematic.

Week 9: An image journal

Wed, 18 Mar 2026 18:21:41 -0500

Nature

The Medellín skyline during a sunset, as seen from El Poblado. Shared by my friend Jerónimo Acosta.

A butterfly I found near the fourth entrance to campus. One of its wings was broken. We kept it for a while, but soon let it go…

Week 7: Migrating to Hugo and playing guitar

Thu, 05 Mar 2026 00:00:00 +0000

Migrating this blog from Bear Blog to Hugo

Why?

I sticked with Bear from the start as I wasn’t planning on doing anything “fancy” with the blog. Now that I’ve thought of adding images for a while, I think it’s time to use a static website generator, such as Hugo, to serve my own content using e.g. GitHub Pages.

Bear costs US$3 per month (after adjusting for Purchasing Power Parity), but it was still not worth it for me, a programmer anyway.

Entropy can, in fact, go down

Tue, 03 Mar 2026 10:38:00 -0500

From Aatishb’s Entropy explained with sheep (emphasis mine):

There’s something curious here. Although the equal energy state is the most likely, it’s still very possible to find all the energy in one solid (the left or right extremes of the graph). In fact, there’s about a 1 in 8 chance of this happening. So the entropy in this system can fluctuate, sometimes going up, other times going down.

So when we look at really tiny solids, energy doesn’t always flow from a hot object to a cold one. It can go the other way sometimes. And entropy doesn’t always increase. This isn’t just a theoretical issue, entropy decreases have actually been seen in microscopic experiments.

Notes on “Principles of Beautiful Figures for Research Papers”

Tue, 03 Mar 2026 10:33:00 -0500

My notes on Andrey Churkin (Андрей Чуркин)’s 2024 video “Principles of Beautiful Figures for Research Papers”.

Journals compress raster images when publishing. Thus it’s better to use vector graphics (SVG for example) to prevent this. Students often don’t know (Oh well, people in general).
Advice: Don’t take screenshots of your computer and put them in a paper.

Even some journals change SVGs to raster (shaking my head). You might have to convert some parts of a graphic for it to be reasonably sized and still readable.

Week 6: Lunch with a mathematician, English, and nature

Mon, 02 Mar 2026 07:15:00 -0500

Lunch with professor María Amelia Salazar

Having lunch at the same time every day can make you loss opportunities to run into people you don’t usually run into. This time, I ran into professor María Amelia Salazar.

A Doctor in Mathematics from Ultrecht University, she used to teach at the Brazilian university Universidade Federal Fluminense in Rio de Janeiro, Brazil. As per her website (linked above), her main research interests are “Lie groupoids, Lie algebroids, Lie pseudogroups, geometry of PDE’s, Poisson geometry, contact and symplectic geometry.”

Week 5: Public libraries, screensavers, and a meeting

Sun, 22 Feb 2026 00:00:00 +0000

On the public libraries map

I made some progress towards my goal of drawing a Voronoi diagram of the nearest public libraries in Medellín. I’m using GeoPandas with Matplotlib and Contextily.

The tiles turned out to be problematic. Contextily just won’t finish at all when I pass the polygon of the Voronoi diagram. It might be the case that it’s trying to download a lot of tiles.

Cellular Automata Screensaver

Since I’m reading this book by Michael Batty on cellular automatas applied to cities, I downloaded a Celullar Automata Screensaver for my Windows laptop:

Zotero plugins I use

Fri, 20 Feb 2026 00:00:00 +0000

The name “Zotero” is loosely based on the Albanian (yes, Albanian) word zotëroj, meaning “to acquire, to master,” as in learning.

From the Zotero documentation

In summary:

Better Bibtex (BBT)

Check out their website.

Lets you auto-export a collection to a .bib file. Useful for compiling with LaTeX locally.

Zutilo

Check out their GitHub repository.

Lets you copy the Zotero URIs or IDs for all kinds of items. Useful for when you want to directly link to a PDF or item.

Week 4: Voronoi, stochastic L-systems, set theory

Mon, 16 Feb 2026 00:00:00 +0000

Trying, and miserably failing, to create that plot

But you know that when the truth is told

That you can get what you want or you can just get old

–Billy Joel, “Vienna”

As I mentioned in the previous entry, I was eager to try my hand at OSMnx plotting to draw a map of the city in a Voronoi diagram sort-of-way… but I failed. You see, I searched for previous work — a.k.a. someone who’s dunnit already — and I found Sabrina Chan’s 2019 blog post. It was quite alright, though it seemed to use Python 2 (instead of Python 3, released in 2008), and wasn’t as plug-and-play as I would have expected. In the end, I tried to tweak their Jupyter Notebook to do the exact same thing for my use case, but it was quite hard. Tomorrow, if I feel like it, I might give it another go. If not, maybe next time around.

Random geography concepts

Sat, 14 Feb 2026 00:00:00 +0000

Continental drip

Continental drip is the observation that southward-pointing landforms are more numerous and prominent than northward-pointing landforms. For example, Africa, South America, the Indian subcontinent, and Greenland all taper off to a point towards the south. The name is a play on continental drift.

[…]

The observation was made by Ormonde de Kay in a 1973 tongue-in-cheek paper, which he introduced as “another earth-shaking new theory derived from simply looking at maps.” It satirizes the acceptance of plate tectonics theory as it was being formulated and refined at the time to describe the movement of the Earth’s continents that is now thoroughly accepted.

Interesting concepts in urban design

Sun, 08 Feb 2026 00:00:00 +0000

This is an ongoing post that I will update as I learn more about urban design.

Road diet

A road diet is when they reduce the number of lanes to make way for other kinds of lanes. There’s a section on the road diet Wikipedia article on § Impacts (e.g. reducing crash frequency, improving incomes, not reducing traffic volumes) that I found interesting.

Permeability and connectivity

You are driving your car along the avenue, when you come across a dead end. Your car is too big to pass through the alleyway, so you park it across the street and travel the rest on foot. That’s what permeability alludes to: what kinds of transport can go through a certain street.

Week 3: New office, lo-fi, papers, and a general meeting

Sat, 07 Feb 2026 00:00:00 -0500

First week in the new office

It seems like it’s been ages since we last worked on the fifth floor of the Engineering Building. I worked there for less than a month, but I was already getting used to the fake wood, the orange atmosphere, the constant strolling about for coffee (not me, as I don’t drink coffee). Not to mention the occasional weird conversations on the other side of the court.

Week 2: Gathering steam

Wed, 28 Jan 2026 10:18:00 -0500

Contracting a contract

We had a few hiccups regarding the official starting date of my contract. An earlier document had set the starting date as the 15th of January. As I mentioned in the previous entry, I dutifully showed up. The Admissions Office wasn’t exactly pleased with my not-having-a-contract-yet-still-showing-up shtick.

Guitar classes

I signed up for guitar classes. We’re starting on Tuesday the 10th of February. Here’s their syllabus from the course page:

Week 1: Starting my internship

Sun, 25 Jan 2026 12:00:00 -0500

Read the About page for context regarding this blog.

First day, sort of

My contract was supposed to start on the 15th of January. That morning, I dutifully packed my laptop and headed to the 6th floor of the Engineering Building.