Blog Archives

Programming with R – Checking Data Types

November 13, 2010
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There are a number of useful functions in R that test the variable type or convert between different variable types. These can be used to validate function input to ensure that sensible answers are returned from a function or to ensure that the function doesn’t fail. Following on from a previous post on a simple function

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Programming with R – Returning Information as a List

November 1, 2010
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In previous posts (here and here) we created a simple function that returns a single numeric value. In some situations it may be more useful to return a more flexible data type, such as a list object, to provide more information about the calculations that have been performed. We can extend our previous function by changing

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Programming with R – Checking Function Arguments

October 24, 2010
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In a previous post we considered writing a simple function to calculate the volume of a cylinder by specifying the height and radius of the cylinder. The function did not have any checking of the validity of the function arguments which we will consider in this post. R has various functions that we can use to

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Programming with R – Function Basics

October 20, 2010
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One of the benefits of using R for statistical analysis is the programming language which allows users to define their own functions, which is particularly useful for analysis that needs to be repeated. For example, a monthly output from a database may be provided in a pre-determined format and we might be interested in running

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Plotting Time Series data using ggplot2

September 30, 2010
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Plotting Time Series data using ggplot2

There are various ways to plot data that is represented by a time series in R. The ggplot2 package has scales that can handle dates reasonably easily. Fast Tube by Casper As an example consider a data set on the number of views of the you tube channel ramstatvid. A short snippet of the data is shown

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Classification Trees using the rpart function

September 21, 2010
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Classification Trees using the rpart function

In a previous post on classification trees we considered using the tree package to fit a classification tree to data divided into known classes. In this post we will look at the alternative function rpart that is available within the base R distribution. Fast Tube by Casper A classification tree can be fitted using the rpart function

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Classification Trees

September 18, 2010
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Classification Trees

Decision trees are applied to situation where data is divided into groups rather than investigating a numerical response and its relationship to a set of descriptor variables. There are various implementations of classification trees in R and the some commonly used functions are rpart and tree. Fast Tube by Casper To illustrate the use of the tree

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Creating a Presentation with LaTeX Beamer – Frame Transitions

September 4, 2010
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Creating a Presentation with LaTeX Beamer – Frame Transitions

Transitions are often used in presentations to break up the presentation and to keep the audience awake, but often the outcome is irritation/distraction with text or other objects flying on or off the screen from different directions. As such they should be used sparingly if at all in a talk. LaTeX beamer has a simple

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Creating a Presentation with LaTeX Beamer – Using Overlays

August 25, 2010
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Creating a Presentation with LaTeX Beamer – Using Overlays

Overlays can be used in a LaTeX beamer presentation to reveal parts of a slide sequentially, which can be a useful way of imparting information to your audience. There are a number of different ways that overlays can be created depending on the sophistication required in the presentation. Fast Tube by Casper The \pause command is the

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Charting the performance of cricket all-rounders – IT Botham

August 16, 2010
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Charting the performance of cricket all-rounders – IT Botham

Cricket is a sport that generates a large volume of performance data and corresponding debate about the relative qualities of various players over their careers and in relation to their contemporaries. The cricinfo website has an extensive database of statistics for professional cricketers that can be searched to access the information in various formats. As an

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