Tag: R

Free Video Lecture: Vectors for Programmers and Data Scientists

We have just released two new free video lectures on vectors from a programmer’s point of view. I am experimenting with what ideas do programmers find interesting about vectors, what concepts do they consider safe starting points, and how to condense and present the material. Please check the lectures out. Vectors for Programmers and Data … Continue reading Free Video Lecture: Vectors for Programmers and Data Scientists

biased sample!

A chance occurrence led me to this thread on R-devel about R sample function generating a bias by taking the integer part of the continuous uniform generator… And then to the note by Kellie Ottoboni and Philip Stark analysing the reason, namely the fact that R uniform [0,1) pseudo-random generator is not perfectly continuously uniform […]

an attempt at code golf

Having discovered codegolf on Stack Exchange a few weeks ago, I spotted a few interesting puzzles since then but only got the opportunity at a try over a quiet and rainy weekend (and Robin being on vacation)! The challenge was to write an R code for deciding whether or not a given integer n is […]

chance call for book reviewers

Since I have been unable to find local reviewers for my CHANCE review column of the above recent CRC Press books, namely Bayesian Cost-Effectiveness Analysis of Medical Treatments, Moreno et al. Combinatorial Inference in Geometric Data Analysis, Le Roux et al. Time Series Clustering and Classification, Maharaj et al. Textual Data Science with R, Bécue-Bertaut […]

easy Riddler

The riddle of the week is rather standard probability calculus If N points are generated at random places on the perimeter of a circle, what is the probability that you can pick a diameter such that all of those points are on only one side of the newly halved circle? Since it is equivalent to […]

a perfectly normally distributed sample

When I saw this title on R-bloggers, I was wondering how “more perfect” a Normal sample could be when compared with the outcome of rnorm(n). Hence went checking the original blog on bayestestR in search of more information. Which was stating nothing more than how to generate a sample is perfectly normal by using the […]

a perfectly normally distributed sample

When I saw this title on R-bloggers, I was wondering how “more perfect” a Normal sample could be when compared with the outcome of rnorm(n). Hence went checking the original blog on bayestestR in search of more information. Which was stating nothing more than how to generate a sample is perfectly normal by using the […]

Could not Resist

Also, Practical Data Science with R, 2nd Edition; Zumel, Mount; Manning 2019 is now content complete! It is deep into editing and soon into production!

visualising bias and unbiasedness

A question on X validated led me to wonder at the point made by Christopher Bishop in his Pattern Recognition and Machine Learning book about the MLE of the Normal variance being biased. As it is illustrated by the above graph that opposes the true and green distribution of the data (made of two points) […]

Le Monde puzzle [#1099]

A simple 2×2 Le Monde mathematical puzzle: Arielle and Brandwein play a game out of two distinct even integers between 1500 and 2500,  and y. Providing one another with either the pair (x/2,y+x/2) or the pair (x+y/2,y/2) until they run out of even possibilities or exceed 6 rounds. When x=2304, what is the value of […]

Data Layout Exercises

John Mount, Nina Zumel; Win-Vector LLC 2019-04-27 In this note we will use five real life examples to demonstrate data layout transforms using the cdata R package. The examples for this note are all demo-examples from tidyr/demo/, and are mostly based on questions posted to StackOverflow. They represent a good cross-section of data layout problems, … Continue reading Data Layout Exercises

Le Monde puzzle [#1094]

A rather blah number Le Monde mathematical puzzle: Find all integer multiples of 11111 with exactly one occurrence of each decimal digit.. Which I solved by brute force, by looking at the possible range of multiples (and  borrowing stringr:str_count from Robin!) > combien=0 > for (i in 90001:900008){ j=i*11111 combien=combien+(min(stringr::str_count(j,paste(0:9)))==1)} > combien [1] 3456 And […]

survivalists [a Riddler’s riddle]

A neat question from The Riddler on a multi-probability survival rate: Nine processes are running in a loop with fixed survivals rates .99,….,.91. What is the probability that the first process is the last one to die? Same question with probabilities .91,…,.99 and the probability that the last process is the last one to die. […]

Le Monde puzzle [#1092]

A Latin square Le Monde mathematical puzzle that I found rather dreary: A hidden 3×3 board contains all numbers from 1 to 9. Anselm wants to guess the board and makes two proposals. Berenicke tells him how many entries are in the right rows and colums for each proposal, along with the information that no […]