In general, foreach is a statement for iterating over items in a collection without using any explicit counter. In R, it is also a way to run code in parallel, which may be more convenient and readable that the sfLapply function (considered in the previous set of exercises of this series) or other apply-alike functions. […]

# Exercises (advanced)

## Parallel Computing Exercises: Snowfall (Part-1)

R has a lot of tools to speed up computations making use of multiple CPU cores either on one computer, or on multiple machines. This series of exercises aims to introduce the basic techniques for implementing parallel computations using multiple CPU cores on one machine. The initial step in preparation for parallelizing computations is to […]

## Data Manipulation with data.table (part -2)

In the last set of exercise of data.table ,we saw some interesting features of data.table .In this set we will cover some of the advanced features like set operation ,join in data.table.You should ideally complete the first part before attempting this one . Answers to the exercises are available here. If you obtained a different […]

## Character Functions (Advanced)

This set of exercises will help you to help you improve your skills with character functions in R. Most of the exercises are related with text mining, a statistical technique that analyses text using statistics. If you find them interesting I would suggest checking the library tm, this includes functions designed for this task. There […]

## Unit testing in R using testthat library Exercises

testthat is a testing framework developed by Hadley Wickham, which makes unit testing easy for developers. Test scripts developed can be re-run after debugging or making changes to the functions without the hassle of developing the code for testing again. testthat has a heirarchical structure made up of expectations, tests and contexts. Visit this link […]

## Plotly : Advanced plots and features

Plotly is a d3 based graphing library used to produce interactive and high quality graphs in R. In the following exercises, we will look at some advanced plots and features avaialable in the package. Please note that the list here is not exhaustive. We will use datasets available in base R packages. You are expected […]

## Descriptive Analytics-Part 6: Interactive dashboard ( 2/2)

Descriptive Analytics is the examination of data or content, usually manually performed, to answer the question “What happened?”.As this series of exercises comes to an end, the last part is going to be the development of a data product. Not everybody is able to code in R, so it is useful to be able to […]

## Descriptive Analytics-Part 6: Interactive dashboard ( 1/2)

Descriptive Analytics is the examination of data or content, usually manually performed, to answer the question “What happened?”.As this series of exercises comes to an end, the last part is going to be the development of a data product. Not everybody is able to code in R, so it is useful to be able to […]

## Descriptive Analytics-Part 5: Data Visualisation (Spatial data)

Descriptive Analytics is the examination of data or content, usually manually performed, to answer the question “What happened?”. In order to be able to solve this set of exercises you should have solved the part 0, part 1, part 2,part 3, and part 4 of this series but also you should run this script which […]

## Repeated measures ANOVA in R Exercises

One way, two way and n way ANOVA are used to test difference in means when we have one, two and n factor variables. A key assumption when performing these ANOVAs is that the measurements are independent. When we have repeated measures this assumption is violated, so we have to use repeated measures ANOVA. Repeated […]