Publications by Corey Chivers
Montreal R User Group meetup Nov. 14th
After a bit of a summer lull, the Montreal R User Group is meeting up again! We’re trying out a new venue this time. Notman House is the home of the web in Montreal. They hold hackathons and other tech user group meetups, and they are all around great people in an all around great space in downtown Montreal. Our meetup will feature R super-user...
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Variable probability Bernoulli outcomes – Fast and Slow
I am working on a project that requires the generation of Bernoulli outcomes. Typically, I would go about this using the built in sample() function like so: sample(1:0,n,prob=c(p,1-p),replace=TRUE) This works great and is fast, even for large n. Problem is, I want to generate each sample with its own unique probability. Seems straight forward en...
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Did the sun just explode? The last Dutch Book you’ll ever make
In today’s XKCD, a pair of (presumably) physicists are told by their neutrino detector that the sun has gone nova. Problem is, the machine rolls two dice and if they both come up six it lies, otherwise it tells the truth. The Frequentist reasons that the probability of obtaining this result if the sun had not, infact, gone nova is 1/36 (0.027,...
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What does R do? Bring people together, of course!
Last night we had a great meet up of the Montreal R User Group. I got things started with a little presentation asking the question “What does R do?” (slides). I made the presentation using Montreal R User Group member Ramnath Vaidyanathan‘s Slidify package. Slidify allows you to generate rather handsome HTML5 slides directly using R markdo...
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IPython vs RStudio+knitr
At a meeting last night with some collaborators at the Vélobstacles project, I was excitedly told about the magic of IPython and it’s notebook functionality for reproducible research. This sounds familiar, I thought to myself. Using a literate programming approach to integrate computation with the communication of methodology and results has b...
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Simulating weak gravitational lensing
In the search for dark matter, I have been having mixed success. It seems that locating DM in single halo skies is a fairly straightforward problem. However, when there are more than one halo, things get quite a bit trickier. As I have advocated many times before, including here and here, simulation can provide deep insights into many (if not all...
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Dark matter top 10, but an hour too late
Well, that’s embarrassing. A little tweak to my dark matter model resulted in a leaderboard score in the top 10. The only problem is that the contest closed about an hour ago. I ran this final prediction earlier today but then simply forgot to go back to it and submit!! On the bright side, I learned a lot of really interesting things about gra...
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Montreal R User group meetup at Wajam
This Thursday (Jan 24th), 5:30pm, the good folks at Wajam are hosting a meetup of the Montreal R User Group. The event will be at Bolidea at 4115 St Laurent, Montréal, QC. Be sure to RSVP. From Benjamin Rollert: This is an opportunity for people interested in R to hang out at our office, eat pizza and drink beer! We’ll also show some of the co...
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The Gambling Machine Puzzle
This puzzle came up in the New York Times Number Play blog. It goes like this: An entrepreneur has devised a gambling machine that chooses two independent random variables x and y that are uniformly and independently distributed between 0 and 100. He plans to tell any customer the value of x and to ask him whether y > x or x > y. If the custome...
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Introduction to Simulation using R
We had a great turnout yesterday for our Zero to R Hero workshop at the Quebec Centre for Biodiversity Science. We went from the absolute basics of the command line, to the intricacies of importing data, and finally we had a look at plotting using ggplot2. We didn’t have time to get to this extra module introducing simulation, but if you want ...
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