# Local Randomness and R

2019-08-14

Let’s say we have a deterministic (non-random) problem for which one of the solutions involves randomness. One very common example of such problem is a function minimization on certain interval: it can be solved non-randomly (like in most methods of optim()), or randomly (the simplest approach being to generate random set of points on interval and to choose the one with the lowest function value).

What is a “clean” way of writing a function to solve the problem? The issue with direct usage of randomness inside a function is that it affects the state of outer random number generation:

Click through for a solution which uses random numbers but doesn’t change the outside world’s random number generation after it’s done.

## From Excel to R: Three Examples

2019-08-21

Abdul Majed Raja has a few examples of things which are easy to do in Excel and how you can do them in R: Create a difference variable between the current value and the next valueThis is also known as lead and lag – especially in a time series dataset this varaible becomes very important in feature engineering. In […]

## Calculating AUC in R

2019-08-20

Andrew Treadway shows how you can calculate Area Under the Curve in R: AUC is an important metric in machine learning for classification. It is often used as a measure of a model’s performance. In effect, AUC is a measure between 0 and 1 of a model’s performance that rank-orders predictions from a model. For […]

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