I used to have a single minor niggle with the BBC News RSS feed: that it included sports news, which I didn’t care
about. So I wrote a script that downloaded it, stripped
sports news, and re-exported the feed for me to subscribe to. Magic.
Lately my BBC News feed has caused me some annoyance and frustration.
But lately – presumably as a result of technical changes at the Beeb’s side – this feed has found two fresh ways to annoy me:
The feed now re-publishes a story if it gets re-promoted to the front page… but with a different<guid> (it appears to get a #0 after it
when first published, a #1 the second time, and so on). In a typical day the feed reader might scoop up new stories about once an hour, any by the time I get to reading them the
same exact story might appear in my reader multiple times. Ugh.
They’ve started adding iPlayer and BBC Sounds content to the BBC News feed. I don’t follow BBC News in my feed reader because I want to watch or listen to things. If
you do, that’s fine, but I don’t, and I’d rather filter this content out.
Luckily, I already have a recipe for improving this feed, thanks to my prior work. Let’s look at my newly-revised script (also available on GitHub):
#!/usr/bin/env rubyrequire'bundler/inline'# # Sample crontab:# # At 41 minutes past each hour, run the script and log the results# */20 * * * * ~/bbc-news-rss-filter-sport-out.rb > ~/bbc-news-rss-filter-sport-out.log 2>>&1# Dependencies:# * open-uri - load remote URL content easily# * nokogiri - parse/filter XML
gemfile do
source 'https://rubygems.org'
gem 'nokogiri'endrequire'open-uri'# Regular expression describing the GUIDs to reject from the resulting RSS feed# We want to drop everything from the "sport" section of the website, also any iPlayer/Sounds linksREJECT_GUIDS_MATCHING=/^https:\/\/www\.bbc\.co\.uk\/(sport|iplayer|sounds)\//# Load and filter the original RSS
rss =Nokogiri::XML(open('https://feeds.bbci.co.uk/news/rss.xml?edition=uk'))
rss.css('item').select{|item| item.css('guid').text =~REJECT_GUIDS_MATCHING }.each(&:unlink)
# Strip the anchors off the <guid>s: BBC News "republishes" stories by using guids with #0, #1, #2 etc, which results in duplicates in feed readers
rss.css('guid').each{|g|g.content=g.content.gsub(/#.*$/,'')}
File.open( '/www/bbc-news-no-sport.xml', 'w' ){ |f| f.puts(rss.to_s) }
It’s amazing what you can do with Nokogiri and a half dozen lines of Ruby.
That revised script removes from the feed anything whose <guid> suggests it’s sports news or from BBC Sounds or iPlayer, and also strips any “anchor” part of the
<guid> before re-exporting the feed. Much better. (Strictly speaking, this can result in a technically-invalid feed by introducing duplicates, but your feed reader
oughta be smart enough to compensate for and ignore that: mine certainly is!)
You’re free to take and adapt the script to your own needs, or – if you don’t mind being tied to my opinions about what should be in BBC News’ RSS feed – just subscribe to my copy at: https://fox.q-t-a.uk/bbc-news-no-sport.xml
My work colleague Simon was looking for a way to add all of the
upcoming UK strike action to their calendar, presumably so they know when not to try to catch a bus or require an ambulance or maybe
just so they’d know to whom they should be giving support on any particular day. Thom was able to suggest a
few places to see lists of strikes, such as this BBC News page and the comprehensive strikecalendar.co.uk, but neither provided a
handy machine-readable feed.
Gosh, there’s a lot of strikes going on. ✊
If only they knew somebody who loves an excuse to throw a screen-scraper together. Oh wait, that’s me!
I threw together a 36-line Ruby program that extracts all the data from strikecalendar.co.uk and outputs an
.ics file. I guess if you wanted you could set it up to automatically update the file a couple of times a day and host it at a URL that people can subscribe to; that’s an exercise left for the reader.
If you just want a one-off import based on the state-of-play right now, though, you can save this .ics file to your computer
and import it to your calendar. Simple.
Suppose you’re running an application on a Passenger + Nginx powered server and you want to add caching.
Perhaps your application has a dynamic, public endpoint but the contents don’t change super-frequently or it isn’t critically-important that the user always gets up-to-the-second
accuracy, and you’d like to improve performance with microcaching. How would you do that?
Where you’re at
Not pictured: the rest of the Internet.
Your configuration might look something like this:
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server {
# listen, server_name, ssl, logging etc. directives go here# ...root/your/application;
passenger_enabledon;
}
What you’re looking for is proxy_cache and its sister directives, but you can’t just
insert them here because while Passenger does act act like an upstream proxy (with parallels like e.g. passenger_pass_header which mirrors the behaviour of proxy_pass_header), it doesn’t provide any of the functions you need to implement proxy caching
of non-static files.
Where you need to be
Instead, what you need to to is define a second server, mount Passenger in that, and then proxy to that second server. E.g.:
# Set up a cacheproxy_cache_path/tmp/cache/my-app-cachekeys_zone=MyAppCache:10mlevels=1:2inactive=600smax_size=100m;
# Define the actual webserver that listens for Internet traffic:server {
# listen, server_name, ssl, logging etc. directives go here# ...# You can configure different rules by location etc., but here's a simple microcache:location/ {
proxy_passhttp://127.0.0.1:4863; # Proxy all traffic to the application server defined belowproxy_cacheMyAppCache; # Use the cache defined aboveproxy_cache_valid2003s; # Treat HTTP 200 responses as valid; cache them for 3 secondsproxy_cache_use_staleupdating; # (Optional) send outdated response while background-updating cacheproxy_cache_lock on; # (Optional) only allow one process to update cache at once
}
}
# (Local-only) application server on an arbitrary port number to act as the upstream proxy:server {
listen 127.0.0.1:4863;
root/your/application;
passenger_enabledon;
}
The two key changes are:
Passenger moves to a second server block, localhost-only, on an arbitrary port number (doesn’t need HTTPS, of course, but if your application detects/”expects” HTTPS you
might need to tweak your headers).
Your main server block proxies to the second as its upstream, and you can add whatever caching directives you like.
Obviously you’ll need to be smarter if you host a mixture of public and private content (e.g. send Vary: headers from your application) and if you want different cache
durations on different addresses or types of content, but there are already great guides to help with that. I only wrote this post because I spent some time searching for (nonexistent!)
passenger_cache_ etc. rules and wanted to save the next person from the same trouble!
Yesterday I recommended that you go read Aaron Uglum‘s webcomic LABS which had just completed its final strip. I’m a big fan of “completed”
webcomics – they feel binge-able in the same way as a complete Netflix series does! – but Spencer quickly pointed out that it’s annoying
for we enlightened modern RSS users who hook RSS up to everything to have to binge completed comics in a different way to reading ongoing ones: what he wanted was an RSS feed covering the entire history of LABS.
With apologies to Aaron Uglum who I hope won’t mind me adapting his comic in this way.
So naturally (after the intense heatwave woke me early this morning anyway) I made one: complete RSS feed of
LABS. And, of course, I open-sourced the code I used to generate it so that others can jumpstart their
projects to make static RSS feeds from completed webcomics, too.
Even if you’re not going to read it via this medium, you should go read LABS.
I love RSS, but it’s a minor niggle for me that if I subscribe to any of the
BBC News RSS feeds I invariably get all the sports
news, too. Which’d be fine if I gave even the slightest care about the world of sports, but I don’t.
If you’d like to see how I did it so you can host it yourself or adapt it for some similar purpose, the code’s below or on GitHub:
#!/usr/bin/env ruby# # Sample crontab:# # At 41 minutes past each hour, run the script and log the results# 41 * * * * ~/bbc-news-rss-filter-sport-out.rb > ~/bbc-news-rss-filter-sport-out.log 2>&1# Dependencies:# * open-uri - load remote URL content easily# * nokogiri - parse/filter XML# * b2 - command line tools, described below
require 'bundler/inline'
gemfile dosource'https://rubygems.org'gem'nokogiri'end
require 'open-uri'# Regular expression describing the GUIDs to reject from the resulting RSS feed# We want to drop everything from the "sport" section of the website
REJECT_GUIDS_MATCHING = /^https:\/\/www\.bbc\.co\.uk\/sport\//# Assumption: you're set up with a Backblaze B2 account with a bucket to which# you'd like to upload the resulting RSS file, and you've configured the 'b2'# command-line tool (https://www.backblaze.com/b2/docs/b2_authorize_account.html)
B2_BUCKET ='YOUR-BUCKET-NAME-GOES-HERE'
B2_FILENAME ='bbc-news-nosport.rss'# Load and filter the original RSS
rss = Nokogiri::XML(open('https://feeds.bbci.co.uk/news/rss.xml?edition=uk'))
rss.css('item').select{|item| item.css('guid').text =~ REJECT_GUIDS_MATCHING }.each(&:unlink)begin# Output resulting filtered RSS into a temporary file
temp_file = Tempfile.new
temp_file.write(rss.to_s)
temp_file.close# Upload filtered RSS to a Backblaze B2 bucket
result =`b2 upload_file --noProgress --contentType application/rss+xml #{B2_BUCKET}#{temp_file.path}#{B2_FILENAME}`putsTime.nowputs result.split("\n").select{|line| line =~ /^URL by file name:/}.join("\n")ensure# Tidy up after ourselves by ensuring we delete the temporary file
temp_file.close
temp_file.unlinkend
Filters it to remove all entries whose GUID matches a particular regular expression (removing all of those from the
“sport” section of the site)
Outputs the resulting feed into a temporary file
Uploads the temporary file to a bucket in Backblaze‘s “B2” repository (think: a better-value competitor S3); the bucket I’m using is
publicly-accessible so anybody’s RSS reader can subscribe to the feed
I like the versatility of the approach I’ve used here and its ability to perform arbitrary mutations on the feed. And I’m a big fan of Nokogiri. In some ways, this could be considered a
lower-impact, less real-time version of my tool RSSey. Aside from the fact that it won’t (easily) handle websites that require Javascript, this
approach could probably be used in exactly the same ways as RSSey, and with significantly less set-up: I might look into whether its functionality can be made more-generic so I can
start using it in more places.
By 2005, Ruby had become more popular, but it was still not a mainstream programming language. That changed with the release of Ruby on Rails. Ruby on Rails was the “killer app” for
Ruby, and it did more than any other project to popularize Ruby. After the release of Ruby on Rails, interest in Ruby shot up across the board, as measured by the TIOBE language
index:
It’s sometimes joked that the only programs anybody writes in Ruby are Ruby-on-Rails web applications. That makes it sound as if Ruby on Rails completely took over the Ruby community,
which is only partly true. While Ruby has certainly come to be known as that language people write Rails apps in, Rails owes as much to Ruby as Ruby owes to Rails.
…
As an early adopter of Ruby (and Rails, when it later came along) I’ve always found that it brings me a level of joy I’ve experienced in very few other languages (and never as much).
Every time I write Ruby, it takes me back to being six years old and hacking BASIC on my family’s microcomputer. Ruby, more than
any other language I’ve come across, achieves the combination of instant satisfaction, minimal surprises, and solid-but-flexible object orientation. There’s so much to love about Ruby
from a technical perspective, but for me: my love of it is emotional.
It’s inevitable these days: we will see an article proclaiming the demise of Ruby on Rails every once in a while. It’s the easiest click bait, like this one from TNW.Now, you may say “another Ruby
fanboy.” That’s fair, but a terrible argument, as it’s a poor and common argumentum ad hominem. And on the subject of
fallacies, the click-bait article above is wrong exactly because it falls for a blatantly Post hoc ergo propter
hoc fallacy plus some more confirmation bias which we are all guilty of falling for all the time.
I’m not saying that the author wrote fallacies on purpose. Unfortunately, it’s just too easy to fall for fallacies. Especially when everybody has an intrinsic desire to confirm
one’s biases. Even trying to be careful, I end up doing that as well…
Together with a friend I recently built Dropshare Cloud. We offer online storage for the file and screenshot sharing app Dropshare for macOS/iOS. After trying out Django for getting started (we both had some experience using
Django) I decided to rewrite the codebase in Rails. My past experience developing in Rails made the process quick — and boring…
Those who know me well know that I’m a bit of a data nerd. Even when I don’t yet know what I’m going to do with some data yet, it feels sensible to start collecting it in a
nice machine-readable format from the word go. Because you never know, right? That’s how I’m able to tell you how much gas and electricity our house used on average on any day in the
last two and a half years (and how much off that was offset by our solar panels).
The red lumps are winters, when the central heating comes on and starts burning a stack of gas.
So it should perhaps come as no huge surprise that for the last six months I’ve been recording the identity of every piece of music played by my favourite local radio station,
Jack FM (don’t worry: I didn’t do this by hand – I wrote a
program to do it). At the time, I wasn’t sure whether there was any point to the exercise… in fact, I’m still not sure. But hey: I’ve got a log of the last 45,000 songs
that the radio station played: I might as well do something with it. The Discogs API proved invaluable in automating the discovery of
metadata relating to each song, such as the year of its release (I wasn’t going to do that by hand either!), and that gave me enough data to, for example, do this (click on any image to
see a bigger version):
Decade frequency by hour: you’ve got a good chance of 80s music at any time, but lunchtime’s your best bet (or perhaps just after midnight). Note that times are in UTC+2 in this
graph.
I almost expected a bigger variance by hour-of-day, but I guess that Jack isn’t in the habit of pandering to its demographics too heavily. I spotted the post-midnight point at which you
get almost a plurality of music from 1990 or later, though: perhaps that’s when the young ‘uns who can still stay up that late are mostly listening to the radio? What about by
day-of-week, then:
Even less in it by day of week… although 70s music fans should consider tuning in on Fridays, apparently, and 80s fans will be happiest on Sundays.
The chunks of “bonus 80s” shouldn’t be surprising, I suppose, given that the radio station advertises that that’s
exactly what it does at those times. But still: it’s reassuring to know that when a radio station claims to play 80s music, you don’t just have to take their word for it
(so long as their listeners include somebody as geeky as me).
It feels to me like every time I tune in they’re playing an INXS song. That can’t be a coincidence, right? Let’s find out:
One in every ten songs are by just ten artists (including INXS). One in every four are by just 34 artists.
Yup, there’s a heavy bias towards Guns ‘n’ Roses, Michael Jackson, Prince, Oasis, Bryan Adams, Madonna, INXS, Bon Jovi, Queen, and U2 (who collectively are responsible for over a tenth
of all music played on Jack FM), and – to a lesser extent – towards Robert Palmer, Meatloaf, Blondie, Green Day, Texas, Whitesnake, the Pet Shop Boys, Billy Idol, Madness, Rainbow,
Elton John, Bruce Springsteen, Aerosmith, Fleetwood Mac, Phil Collins, ZZ Top, AC/DC, Duran Duran, the Police, Simple Minds, Blur, David Bowie, Def Leppard, and REM: taken together, one
in every four songs played on Jack FM is by one of these 34 artists.
Amazingly, the most-played song on Jack FM (Alice Cooper’s “Poison”) is not by one of the most-played 34 artists.
I was interested to see that the “top 20 songs” played on Jack FM these last six months include several songs by artists who otherwise aren’t represented at all on the station. The
most-played song is Alice Cooper’s Poison, but I’ve never recorded them playing any other Alice Cooper songs (boo!). The fifth-most-played song is Fight For Your
Right, by the Beastie Boys, but that’s the only Beastie Boys song I’ve caught them playing. And the seventh-most-played – Roachford’s Cuddly Toy – is similarly the only
Roachford song they ever put on.
Next I tried a Markov chain analysis. Markov chains are a mathematical tool that examines a sequence (in this case, a sequence
of songs) and builds a map of “chains” of sequential songs, recording the frequency with which they follow one another – here’s a great
explanation and playground. The same technique is used by “predictive text” features on your smartphone: it knows what word to suggest you type next based on the patterns of words
you most-often type in sequence. And running some Markov chain analysis helped me find some really… interesting patterns in the playlists. For example, look at the similarities between
what was played early in the afternoon of Wednesday 19 October and what was played 12 hours later, early in the morning of Thursday 20 October:
19 October 2016
20 October 2016
12:06:33
Kool & The Gang – Fresh
Kool & The Gang – Fresh
00:13:56
12:10:35
Bruce Springsteen – Dancing In The Dark
Bruce Springsteen – Dancing In The Dark
00:17:57
12:14:36
Maxi Priest – Close To You
Maxi Priest – Close To You
00:21:59
12:22:38
Van Halen – Why Can’t This Be Love
Van Halen – Why Can’t This Be Love
00:25:00
12:25:39
Beats International / Lindy – Dub Be Good To Me
Beats International / Lindy – Dub Be Good To Me
00:29:01
12:29:40
Kasabian – Fire
Kasabian – Fire
00:33:02
12:33:42
Talk Talk – It’s My Life
Talk Talk – It’s My Life
00:38:04
12:41:44
Lenny Kravitz – Are You Gonna Go My Way
Lenny Kravitz – Are You Gonna Go My Way
00:42:05
12:45:45
Shalamar – I Can Make You Feel Good
Shalamar – I Can Make You Feel Good
00:45:06
12:49:47
4 Non Blondes – What’s Up
4 Non Blondes – What’s Up
00:50:07
12:55:49
Madness – Baggy Trousers
Madness – Baggy Trousers
00:54:09
Eagle Eye Cherry – Save Tonight
00:56:09
Feeling – Love It When You Call
01:04:12
13:02:51
Fine Young Cannibals – Good Thing
Fine Young Cannibals – Good Thing
01:10:14
13:06:54
Blur – There’s No Other Way
Blur – There’s No Other Way
01:14:15
13:09:55
Pet Shop Boys – It’s A Sin
Pet Shop Boys – It’s A Sin
01:17:16
13:14:56
Zutons – Valerie
Zutons – Valerie
01:22:18
13:22:59
Cure – The Love Cats
Cure – The Love Cats
01:26:19
13:27:01
Bryan Adams / Mel C – When You’re Gone
Bryan Adams / Mel C – When You’re Gone
01:30:20
13:30:02
Depeche Mode – Personal Jesus
Depeche Mode – Personal Jesus
01:33:21
13:34:03
Queen – Another One Bites The Dust
Queen – Another One Bites The Dust
01:38:22
13:42:06
Shania Twain – That Don’t Impress Me Much
Shania Twain – That Don’t Impress Me Much
01:42:23
13:45:07
ZZ Top – Gimme All Your Lovin’
ZZ Top – Gimme All Your Lovin’
01:46:25
13:49:09
Abba – Mamma Mia
Abba – Mamma Mia
01:50:26
13:53:10
Survivor – Eye Of The Tiger
Survivor – Eye Of The Tiger
01:53:27
Scouting For Girls – Elvis Aint Dead
01:57:28
Verve – Lucky Man
02:00:29
Fleetwood Mac – Say You Love Me
02:05:30
14:03:13
Kiss – Crazy Crazy Nights
Kiss – Crazy Crazy Nights
02:10:31
14:07:15
Lightning Seeds – Sense
Lightning Seeds – Sense
02:14:33
14:11:16
Pretenders – Brass In Pocket
Pretenders – Brass In Pocket
02:18:34
14:14:17
Elvis Presley / JXL – A Little Less Conversation
Elvis Presley / JXL – A Little Less Conversation
02:21:35
14:22:19
U2 – Angel Of Harlem
U2 – Angel Of Harlem
02:24:36
14:25:20
Trammps – Disco Inferno
Trammps – Disco Inferno
02:28:37
14:29:22
Cast – Guiding Star
Cast – Guiding Star
02:31:38
14:33:23
New Order – Blue Monday
New Order – Blue Monday
02:36:39
14:41:26
Def Leppard – Let’s Get Rocked
Def Leppard – Let’s Get Rocked
02:40:41
14:46:28
Phil Collins – Sussudio
Phil Collins – Sussudio
02:45:42
14:50:30
Shawn Mullins – Lullaby
Shawn Mullins – Lullaby
02:49:43
14:55:31
Stars On 45 – Stars On 45
Stars On 45 – Stars On 45
02:53:45
16:06:35
Dead Or Alive – You Spin Me Round Like A Record
Dead Or Alive – You Spin Me Round Like A Record
03:00:47
16:09:36
Dire Straits – Walk Of Life
Dire Straits – Walk Of Life
03:03:48
16:13:37
Keane – Everybody’s Changing
Keane – Everybody’s Changing
03:07:49
16:17:39
Billy Idol – Rebel Yell
Billy Idol – Rebel Yell
03:10:50
16:25:41
Stealers Wheel – Stuck In The Middle
Stealers Wheel – Stuck In The Middle
03:14:51
16:28:42
Green Day – American Idiot
Green Day – American Idiot
03:18:52
16:33:44
A-Ha – Take On Me
A-Ha – Take On Me
03:21:53
16:36:45
Cranberries – Dreams
Cranberries – Dreams
03:26:54
Elton John – Philadelphia Freedom
03:30:56
Inxs – Disappear
03:36:57
Kim Wilde – You Keep Me Hanging On
03:40:59
16:44:47
Living In A Box – Living In A Box
16:47:48
Status Quo – Rockin’ All Over The World
Status Quo – Rockin’ All Over The World
03:45:00
The similarities between those playlists (which include a 20-songs-in-a-row streak!) surely can’t be coincidence… but they do go some way to explaining why listening to Jack FM
sometimes gives me a feeling of déjà vu (along with, perhaps, the no-talk, all-jukebox format). Looking
elsewhere in the data I found dozens of other similar occurances, though none that were both such long chains and in such close proximity to one another. What does it mean?
There are several possible explanations, including:
The exotic, e.g. they’re using Markov chains to control an auto-DJ, and so just sometimes it randomly chooses to follow a long chain that it “learned” from a real DJ.
The silly, e.g. Jack FM somehow knew that I was monitoring them in this way and are trying to troll me.
My favourite: these two are actually the same playlist, but with breaks interspersed differently. During the daytime, the breaks in the list are more-frequent and longer,
which suggests: ad breaks! Advertisers are far more-likely to pay for spots during the mid-afternoon than they are in the middle of the night (the gap in the overnight playlist could
well be a short ad or a jingle), which would explain why the two are different from one another!
But the question remains: why reuse playlists in close proximity at all? Even when the station operates autonomously, as it clearly does most of the time, it’d surely be easy enough to
set up an auto-DJ using “smart random” (because truly
random shuffles don’t sound random to humans) to get the same or a better effect.
One of the things I love about Jack FM is how little they take seriously. Like their style guide.
Which leads to another interesting observation: Jack FM’s sister stations in Surrey and Hampshire also maintain a similar playlist most of the time… which means that they’re either
synchronising their ad breaks (including their duration – I suspect this is the case) or else using filler jingles to line-up content with the beginnings and ends of songs. It’s a
clever operation, clearly, but it’s not beyond black-box comprehension. More research is clearly needed. (And yes, I’m sure I could just call up and ask – they call me “Newcastle Dan”
on the breakfast show – but that wouldn’t be even half as fun as the data mining is…)
I’ve spent the last couple of weeks digging into some of the newer/fancier/shinier technologies that have been in the limelight of the development world lately – specifically Elixir,
Phoenix and Elm – and while I’ve thoroughly enjoyed them all (and instantly had a bunch of fun ideas for things to build with them), I also realized once more how much I like Ruby,
and what kind of project it’s still a great choice for…
It’s common for a Ruby developer to describe themselves as a Rails developer. It’s also common for someone’s entire Ruby experience to be through Rails. Rails began in 2003 by David
Heinemeier Hansson, quickly becoming the most popular web framework and also serving as an introduction to Ruby for many developers.
Rails is great. I use it every day for my job, it was my introduction to Ruby, and this is the most fun I’ve ever had as a developer. That being said, there are a number of great
framework options out there that aren’t Rails.
This article intends to highlight the differences between Cuba, Sinatra, Padrino, Lotus, and how they compare to or differ from Rails. Let’s have a look at some Non-Rails Frameworks
in Ruby.
What’s the hardest word to guess, when playing hangman? I’ll come back to that.
Whatever could the missing letter be?
Last year, Nick Berry wrote a fantastic blog post about the optimal strategy for Hangman. He showed that the best guesses
to make to get your first “hit” in a game of hangman are not the most-commonly occurring letters in written English, because these aren’t the most commonly-occurring
letters in individual words. He also showed that the first guesses should be adjusted based on the length of the word (the most common letter in 5-letter words is ‘S’, but the most
common letter in 6-letter words is ‘E’). In short: hangman’s a more-complex game than you probably thought it was! I’d like to take his work a step further, and work out which word is
the hardest word: that is – assuming you’re playing an optimal strategy, what word takes the most-guesses?
The rules of hangman used to be a lot more brutal. Nowadays, very few people die as a result of the game.
First, though, we need to understand how hangman is perfectly played. Based on the assumption that the “executioner” player is choosing words randomly, and that no clue is given as to
the nature of the word, we can determine the best possible move for all possible states of the game by using a data structure known as a tree. Suppose our opponent has chosen a
three-letter word, and has drawn three dashes to indicate this. We know from Nick’s article that the best letter to guess is A. And then, if our guess is wrong, the next
best letter to guess is E. But what if our first guess is right? Well, then we’ve got an “A” in one or more positions on the board, and we need to work out the next best
move: it’s unlikely to be “E” – very few three-letter words have both an “A” and an “E” – and of course what letter we should guess next depends entirely on what positions
the letters are in.
There are billions of possible states of game play, but you can narrow them down quickly with strategic guessing.
What we’re actually doing here is a filtering exercise: of all of the possible letters we could choose, we’re considering what possible results that could have. Then for
each of those results, we’re considering what guesses we could make next, and so on. At each stage, we compare all of the possible moves to a dictionary of all possible
words, and filter out all of the words it can’t be: after our first guess in the diagram above, if we guess “A” and the board now shows “_ A _”, then we know that of the
600+ three-letter words in the English language, we’re dealing with one of only about 134. We further refine our guess by playing the odds: of those words, more of them have a “C” in
than any other letter, so that’s our second guess. If it has a C in, that limits the options further, and we can plan the next guess accordingly. If it doesn’t have a C
in, that still provides us with valuable information: we’re now looking for a three-letter word with an A in the second position and no letter C: that cuts it
down to 124 words (and our next guess should be ‘T’). This tree-based mechanism for working out the best moves is comparable to that used by other game-playing computers. Hangman is
simple enough that it can be “solved” by contemporary computers (like draughts –
solved in 2007 – but unlike chess: while modern chess-playing
computers can beat humans, it’s still theoretically possible to build future computers that will beat today’s computers).
Zen Hangman asks the really important questions. If a man has one guess left and refuses to pick a letter, does he live forever, or not at all?
Now that we can simulate the way that a perfect player would play against a truly-random executioner, we can use this to simulate games of hangman for every possible word
(I’m using version 0.7 of this British-English dictionary).
In other words, we set up two computer players: the first chooses a word from the dictionary, the second plays “perfectly” to try to guess the word, and we record how many guesses it
took. So that’s what I did. Here’s the Ruby code I used. It’s heavily-commented and
probably pretty understandable/good learning material, if you’re into that kind of thing. Or if you fancy optimising it, there’s plenty of scope for that too (I knocked it out on a
lunch break; don’t expect too much!). Or you could use it as the basis to make a playable hangman game. Go wild.
The hardest three-letter hangman words. “Sly” is particularly… well, sly.
Running the program, we can see that the hardest three-letter word is “xxv”, which would take 22 guesses (20 of them wrong!) to get. But aside from the roman numeral for 25, I don’t
think that “xxv” is actually a word. Perhaps my dictionary’s not very good. “Oak”, though, is definitely a word, and at 20 guesses (17 wrong), it’s easily enough to hang your opponent
no matter how many strokes it takes to complete the gallows.
Interestingly, “oaks” is an easier word than “oak” (although it’s still very difficult): the addition of an extra letter to a word does not make it harder, especially when that letter
is common.
There are more tougher words in the four-letter set, like the devious “quiz”, “jazz”, “zinc”, and “faux”. Pick one of those and your opponent – unless they’ve seen this blog post! – is
incredibly unlikely to guess it before they’re swinging from a rope.
“Hazing foxes, fucking cockily” is not only the title of a highly-inappropriate animated film, but also a series of very challenging Hangman words.
As we get into the 5, 6, and 7-letter words you’ll begin to notice a pattern: that the hardest words with any given number of letters get easier the longer
they are. That’s kind of what you’d expect, I suppose: if there were a hypothetical word that contained every letter in the alphabet, then nobody would ever fail to (eventually) get it.
Some of the longer words are wonderful, like: dysprosium, semivowel, harrumph, and googolplex.
When we make a graph of each word length, showing which proportion of the words require a given number of “wrong” guesses (by an optimised player), we discover a “sweet spot” window in
which we’ll find all of the words that an optimised player will always fail to guess (assuming that we permit up to 10 incorrect guesses before they’re disqualified). The
window seems small for the number of times I remember seeing people actually lose at hangman, which implies to me that human players consistently play sub-optimally, and do not
adequately counteract that failing by applying an equal level of “smart”, intuitive play (knowing one’s opponent and their vocabulary, looking for hints in the way the game is
presented, etc.).
The “sweet spot” in the bottom right is the set of words which you would expect a perfect player to fail to guess, assuming that they’re given a limit of 10 “wrong” guesses.
In case you’re interested, then, here are the theoretically-hardest words to throw at your hangman opponent. While many of the words there feel like they would quite-rightly be
difficult, others feel like they’d be easier than their ranking would imply: this is probably because they contain unusual numbers of vowels or vowels in unusual-but-telling positions,
which humans (with their habit, inefficient under normal circumstances, of guessing an extended series of vowels to begin with) might be faster to guess than a
computer.
