notes in a shoebox
Between covid-19 news and announcements of imminent Russia-Ukraine wars I needed a bit of a distraction. Sooo, here it is how to create an n x n autocorrelation matrix based on a correlation rho, with a simple 5 x 5 example in R:
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n <- 5 rho <- 0.9 mat <- diag(n) mat <- rho^abs(row(mat) - col(mat)) |
This produces the following output: A 5 x 5 autocorrelation matrix… Continue reading Creating an n x n autocorrelation matrix
I came across this problem in Twitter: Description of the problem by Fermat's Library. The basic pieces of the problem are: We need to generate pseudorandom numbers with an identical distribution, add them up until they go over 1 and report back how many numbers we needed to achieve that condition.Well, do the above "quite… Continue reading The beauty of code vectorisation
I think programming, aka coding, is a fun activity. We are solving a problem subject to a set of constraints that can be time, memory, quantity of code, language, etc. Besides being a part of my work, coding is also a good distraction when doing it for the sake of it. In this type of… Continue reading Recreational programming
In our research group we often have people creating statistical models that end up in publications but, most of the time, the practical implementation of those models is lacking. I mean, we have a bunch of barely functioning code that is very difficult to use in a reliable way in operations of the breeding programs.… Continue reading Implementing a model as an R package
One of the tools we use in our research is NIR (Near-Infrared Spectroscopy), which we apply to thousands of samples to predict their chemical composition. Each NIR spectrum is contained in a CSV text file with two numerical columns: wavelength and reflectance. All files have the same number of rows (1296 in our case), which… Continue reading Reading a folder with many small files
