Cleveland’s Dot Plots for Plotting Data

September 26th, 2009

The dot plot was introduced by Cleveland to provide a powerful visual display to compare groups of data and a function for this type of graphical display is available in the lattice library for R. Data is divided into groups and dots are used to indicate the value of a particular variable with the groups arranged either horizontally or vertically to allow a visual comparison of the distributions for the groups. Read the rest of this entry »

Solving Linear Programming Problems with the Gnu Linear Programming Kit

September 20th, 2009

The GNU Linear Programming Kit (GLPK) can be accessed in R and used for solving large-scale linear programming (LP), mixed integer programming (MIP) and other scenarios. The Rglpk package can be installed and provides a simple interface to using the GLPK. Read the rest of this entry »

Lattice Graphics Book – Examples Website

September 15th, 2009

The author of the lattice graphics library has written a book describing using lattice graphics which provides a large number of examples. A website has been created that shows the graphs using different colour schemes and shows the code that has been used to construct the plots. Read the rest of this entry »

A Gallery of Graphs produced using R

September 12th, 2009

The R environment for Statistical Analysis has strong facilities for producing high quality graphical output. There are many books and electronic documents that demonstrate examples of effective ways to display data graphically. To get an feel for the range of display that could be used it is worthwhile visiting the R Graph Gallery. Read the rest of this entry »

Creating Date Objects using Character Strings

September 10th, 2009

The use of dates can frequently be problematic because there is such a wide range of format used to store data information. The R system has various facilities for defining and working with dates and can handle a wide range of formats that might be encountered in a set of data. Read the rest of this entry »

Program Flow – Loops

September 4th, 2009

The R programming language has keywords defined to allow the user to defined loops in various ways – as a for, while or repeat statement. These statements can be used to ensure that a section of code is repeated multiple times until a defined condition has been satisfied. Read the rest of this entry »