Articles by S. Richter-Walsh

Cats are great and so is the forcats R package

March 28, 2018 |

Cats are great. Perhaps Hadley Wickham and Lionel Henry think so too given the wonderful choice of name for their purrr package. Hadley Wickham has also created a superb package called forcats, likely  an abbreviation of “for categoricals” but wittingly cat-themed, which is very, very useful to the data scientist. ...

Useful dplyr Functions (w/examples)

July 10, 2017 |

The R package dplyr is an extremely useful resource for data cleaning, manipulation, visualisation and analysis. It contains a large number of very useful functions and is, without doubt, one of my top 3 R packages today (ggplot2 and reshape2 being the others). When I was learning how to use dplyr ... [Read more...]

Ordinary Least Squares (OLS) Linear Regression in R

July 4, 2017 |

Ordinary Least Squares (OLS) linear regression is a statistical technique used for the analysis and modelling of linear relationships between a response variable and one or more predictor variables. If the relationship between two variables appears to be linear, then a straight line can be fit to the data in ...

Bland-Altman/Tukey Mean-Difference Plots using ggplot2

May 31, 2017 |

A very useful data visualisation tool in science, particularly in medical and sports settings, is the Bland-Altman/Tukey Mean-Difference plot. When comparing two sets of measurements for the same variable made by different instruments, it is often required to determine whether the instruments are in agreement or not. Correlation and ...

ggplot2 style plotting in Python

May 8, 2017 |

R is my language of choice for data science but a good data scientist should have some knowledge of all of the great tools available to them. Recently, I have been gleefully using Python for machine learning problems (specifically pandas and the wonderful scikit-learn). However, for all its greatness, I ...

Naive Bayes Classification in R (Part 2)

February 17, 2017 |

Following on from Part 1 of this two-part post, I would now like to explain how the Naive Bayes classifier works before applying it to a classification problem involving breast cancer data. The dataset is sourced from Matjaz Zwitter and Milan Soklic from the Institute of Oncology, University Medical Center in ... [Read more...]

Naive Bayes Classification in R (Part 1)

February 17, 2017 |

Introduction A very useful machine learning method which, for its simplicity, is incredibly successful in many real world applications is the Naive Bayes classifier. I am currently taking a machine learning module as part of my data science college course and this week’s practical work involved a classification problem ... [Read more...]

Implementing the Gradient Descent Algorithm in R

February 12, 2017 |

A Brief Introduction Linear regression is a classic supervised statistical technique for predictive modelling which is based on the linear hypothesis: y = mx + c where y is the response or outcome variable, m is the gradient of the linear trend-line, x is the predictor variable and c is the intercept. ...

Predicting the Willingen 2017 men’s ski jumping competition

January 26, 2017 |

In an earlier post of mine, I carried out an analysis on ski jumping data for Zakopane, Poland and attempted to predict which athletes would end up on the podium. I also created a classification tree and tested it on the 2017 competition data with good results. For this side project ...

IMDB Movie Analysis

January 19, 2017 |

Movies of late haven’t impressed (this viewer anyhow) and I keep finding myself returning to classics of the 1980’s and 1990’s to get my movie fix. While browsing through Kaggle datasets, I came across the IMDB 5000 Movie Dataset which contains data on over 5000 movies scraped from the IMDB website. ...

An Analysis of Global Shark Attacks between 1543-2016

January 17, 2017 |

Travelling to a warm country and plan on hitting the beach? “Beware of the sharks!!” While the expression has almost become a cliché at this stage, shark attacks do occur and the fact that the global ocean is heating up potentially facilitates the occurrence of attacks (I would refer to ...

Predicting the Zakopane 2017 men’s ski jumping competition

January 16, 2017 |

When I was a young boy with a wild imagination, I used to try my hand at numerous sports ranging from tennis to gaelic footbal to soccer, each with varying degrees of success. Living in the countryside throughout my childhood, a big garden allowed me to construct vivid simulations of ...

The other carbon dioxide problem.

August 2, 2015 |

Researchers say ocean acidification may have dramatic effects on phytoplankton. Edit section Phytoplankton, tiny plants which live in the ocean, form the foundation of the marine food web and play an important role in the regulation of Earth’s climate. These wonderful organisms create their own food using sunlight, nutrients ...

Reflections

July 31, 2013 |

We know much as a species yet we have so much more to learn. Each of us alive today could just as easily have been born into consciousness centuries or millenia ago, and have had little idea that the Earth revolved around the Sun nor that our solar system was ...