Brendan Halpin
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bthalpin.mastodon.social.ap.brid.gy
Brendan Halpin
@bthalpin.mastodon.social.ap.brid.gy
44 followers 3 following 490 posts
Sociologist in Limerick

Mostly playing with unrealistic computer models of real world processes

Emacs, Stata, Shiny & Rstats, Julia, Python

Linux on the […]

[bridged from https://mastodon.social/@bthalpin on the fediverse by https://fed.brid.gy/ ]
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bthalpin.mastodon.social.ap.brid.gy
#stormbram seems to be affecting the southeast most
Repeated maps of Ireland at halfhour intervals today, showing power outages, mostly in the southeast, mostly in the afternoon
December 9, 2025 at 5:14 PM
bthalpin.mastodon.social.ap.brid.gy
We're not made of sugar. We're made of sterner stuff than the coders or this weather app!
Screenshot of forecast summary showing light to dense intensity drizzle for the next week
December 5, 2025 at 7:22 PM
bthalpin.mastodon.social.ap.brid.gy
Even my browser doesn't think islamophobia is a word🤦
Screenshot of previous post in edit box, islamophobia underlined with wavy red line
November 17, 2025 at 4:54 PM
bthalpin.mastodon.social.ap.brid.gy
The DST switch has two advantages: moving an hour of summer daylight we'd normally sleep through into our evenings, and reducing the variation in the time of sunrise (avoid dark mornings).

A 1-hour adjustment makes quite a big difference in middle latitudes […]

[Original post on mastodon.social]
Line graph showing time difference between latest and earliest sunrise, by latitude. Close to zero at the equator (effect of elliptical orbit), rising steadily, c2.5 at 40°, c6.5 at 60°. A little north of 63° there is no sunrise part of the year.
November 3, 2025 at 4:14 PM
bthalpin.mastodon.social.ap.brid.gy
Playing with #julialang and GEOjson.jl, trying to figure out how to draw Irish constituency maps from https://osi.maps.arcgis.com/home/item.html?id=322f308d929f4f03960fa42513482d8a

Far too much detail! But the polygons! Three constituencies have more than 100 polygons, Galway has 277!!!
Constituency map for Ireland (Republic, obvs) with Cork Southwest, Galway, Mayo and Donegal in red: lots of islands, lots of polygons
October 27, 2025 at 3:31 PM
bthalpin.mastodon.social.ap.brid.gy
Puzzle: A + B = C

Answers on a postcard

#mastodaoine
Bald male 1 Bald male 2 Bald male 3
October 25, 2025 at 8:38 PM
bthalpin.mastodon.social.ap.brid.gy
I had fun with OpenStreetMap data and Julia yesterday, so I wrote some notes on how I did it (i.e., access OSM data, process it with Shapefile.jl and plot it with Plots.jl).

Details at https://brendanhalpin.net/blog/osmnjulia
Minimal map of Limerick city, containing only paths (roads, cycleways, footpaths). Service roads in grey, cycleways in blue, other in dark red.
October 3, 2025 at 10:59 PM
bthalpin.mastodon.social.ap.brid.gy
I haven't been paying attention, but apparently it's been a bit stormy today.

#mastodaoine
Line graph showing a count of electrical outages in Ireland over 2+ weeks, mostly under 5, peaking at over 450 just now. Based on https://powercheck.ie.
October 3, 2025 at 9:42 PM
bthalpin.mastodon.social.ap.brid.gy
Anyone recognise this place?

#openstreetmap #julialang #mastodaoine
Map drawn from OSM road/path data, service roads in grey, biketracks in blue, otherwise in dark red
October 3, 2025 at 10:08 AM
bthalpin.mastodon.social.ap.brid.gy
A map of Ireland (north and south) drawn only with motorways, primary and trunk roads, from OSM data provided as shapefiles from https://download.geofabrik.de/europe/ireland-and-northern-ireland.html (updated daily).

Decoded and drawn entirely with Julia […]

[Original post on mastodon.social]
Map if the island of Ireland drawn only with major roads
October 2, 2025 at 9:21 PM
bthalpin.mastodon.social.ap.brid.gy
Of FFS! #brightspace is fucking up my #julialang teaching materials for tomorrow by being too clever.

It can interpret latex code and show formula. Brilliant.

It just can't not do it, so my regular expression example of

r"\\([0-9]+\\)") is showing up as […]

[Original post on mastodon.social]
Code example r"[0-9]+" where the [0-9]+ is in Latex format, Computer Modern Roman font, instead of the r"\([0-9]+\)" required.
September 30, 2025 at 11:48 PM
bthalpin.mastodon.social.ap.brid.gy
Maria Steen and husband, with two entirely unrelated images

What a pity we're not going to hear from her as much as if she had been nominated.

#mastodaoine
Maria Steen and husband, outside Oireachtas, on her failure to be nominated for the Irish presidential election. Sharp shoes, and her husband reminds me of someone Lotte Lenya/Rosa Klebb's sharp shoes from "From Russia with Love" Image of Groucho Marx mask (bushy eyebrows, big glasses, big nose, bushy tache)
September 24, 2025 at 4:51 PM
bthalpin.mastodon.social.ap.brid.gy
The R/tidyverse "pipe" tri-graph reminds me of something but I can't put my finger on it...

%>%
Barney Rubble from the Flintstones, in a doorway, laughing helplessly with his eyes closed
September 22, 2025 at 3:47 PM
bthalpin.mastodon.social.ap.brid.gy
I'm putting together notes for novices to do simple data analysis with R and the fact that I'm telling them to "cut and paste this inscrutable block of code at the start of your file" reminds me of nothing so much as when I worked for the ESRI in Dublin in […]

[Original post on mastodon.social]
Block of R code: library(data.table) library(ggplot2) library(epiDisplay) library(foreign) nlsw88 = read.dta("nlsw88.dta")
September 6, 2025 at 12:30 PM
bthalpin.mastodon.social.ap.brid.gy
Looking for the local tides, and Duckduckgo helpfully gives me an AI summary that is approx 6 hrs out. Which is about as wrong as you can be.
AI Overview   +1 Les marées à Xxxxxx aujourd'hui, mardi 12 août 2025, sont les suivantes : la marée haute sera à 03h05 et 15h22, et la marée basse à 08h58 et 21h13. Le coefficient de marée est de 95, selon les prévisions de Météo Marine. 
August 12, 2025 at 9:27 PM
bthalpin.mastodon.social.ap.brid.gy
I'm on a (v fast) train
Line graph of speed over distance showing sustained 300km/h (with noise)
July 27, 2025 at 9:41 AM
bthalpin.mastodon.social.ap.brid.gy
July 14, 2025 at 7:26 PM
bthalpin.mastodon.social.ap.brid.gy
I also looked at elevation. The old phone has been pretty poor at this, but I assumed that was just a GPS thing (comparing GPS elevation with e.g., SRTM elevation shows the phone can be slow to respond (ofc GPS and local height above sea level don't agree)) […]

[Original post on mastodon.social]
Elevation by time, now. The new phone is higher as we climb, but lower as we decline. Elevation rises steeply initially, flattens, and shows a circa 30 minute downhill.
July 8, 2025 at 10:14 PM
bthalpin.mastodon.social.ap.brid.gy
Time on the X-axis might make more sense. Shows that grinding up the hill takes longer!
The x-axis is now time, not distance, so the slow bits take longer!
July 8, 2025 at 10:10 PM
bthalpin.mastodon.social.ap.brid.gy
I replaced my ancient phone with a Fairphone 5 and decided to do the ultimate comparison test: how accurate is the GPS when I'm riding my bike? Answer: on a map the tracks are v close but the F5 is consistently better, fewer wobbles. Errors in location mean […]

[Original post on mastodon.social]
Line graph of speed by distance, two records largely in agreement but the old phone's one distinctly more jittery.
July 8, 2025 at 9:46 PM
bthalpin.mastodon.social.ap.brid.gy
Solstice thought: the earth's transit around the sun is like climbing the spiral staircase of the Tower of Pisa. You begin leaning left, after 1/4 you're more or less upright, 1/4 further leaning right, then upright again. Then left again, etc.
Leaning Tower of Pisa partly obscured by a cypress
June 20, 2025 at 6:18 PM
bthalpin.mastodon.social.ap.brid.gy
"No tractors" sign as used on French autoroutes
May 26, 2025 at 1:04 PM
bthalpin.mastodon.social.ap.brid.gy
My old bike* is permanently out of commission, and I'm temporarily on a borrowed bike. It's fine, but it felt not quite right. I swapped over my old saddle (Brooks¸c20yrs old) and, with the help of a tape-measure, adjusted the positioning to be as close as […]

[Original post on mastodon.social]
The remains of my bottom bracket after the mechanic tried and failed to remove the cup, locked in place by corrosion
May 20, 2025 at 12:25 PM
bthalpin.mastodon.social.ap.brid.gy
My new pedagogical philosophy
Homer meme, originally "Beer, the cause of, and solution to, all our problems"; with "ChatGPT! replacing beer
May 18, 2025 at 11:19 PM
bthalpin.mastodon.social.ap.brid.gy
I've made a machine on my home network externally visible. Not without putting fail2ban on it, of course, to protect against ssh brute force attacks.

I decided to track fail2ban's activity, specifically the number of currently banned hosts. Constant attacks, but what a spike on May 6!
Line graph showing number of fail2ban currently banned hosts by time, May 2 to May 13. Almost always between 10 and 30 approx, but spiking over 100 for a brief period on May 6.
May 14, 2025 at 8:57 AM