Articles by Tony Breyal

R: Stem (Pre-Processed) Text Blocks

August 24, 2014 | Tony Breyal

Objective I recently needed to stem every word in a block of text i.e. reduce each word to a root form. Problem The stemmer I was using would only stem the last word in each block of text e.g. Solution I wrote a function which splits a block ... [Read more...]

R: A Quick Scrape of Top Grossing Films from boxofficemojo.com

January 13, 2012 | Tony Breyal

Introduction I was looking at a list of the top grossing films of all time (available from boxofficemojo.com) and was wondering what kind of graphs I would come up with if I had that kind of data. I still don’t know what kind of graphs I’d construct ... [Read more...]

R: Web Scraping R-bloggers Facebook Page

January 6, 2012 | Tony Breyal

Introduction R-bloggers.com is a blog aggregator maintained by Tal Galili. It is a great website for both learning about R and keeping up-to-date with the latest developments (because someone will probably, and very kindly, post about the status of some R related feature). There is also an R-bloggers facebook ...

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Plotting Doctor Who Ratings (1963-2011) with R

January 3, 2012 | Tony Breyal

Introduction First day back to work after New Year celebrations and my brain doesn’t really want to think too much. So I went out for lunch and had a nice walk in the park. Still had 15 minutes to kill before my lunch break was over and so decided to ... [Read more...]

Unshorten (almost) any URL with R

December 13, 2011 | Tony Breyal

Introduction I was asked by a friend how to find the full final address of an URL which had been shortened via a shortening service (e.g., Twitter’s t.co, Google’s goo.gl, Facebook’s fb.me, dft.ba, bit.ly, TinyURL, tr.im, Ow.ly, etc.). I ... [Read more...]

Code Optimization: One R Problem, Thirteen Solutions – Now Sixteen!

December 8, 2011 | Tony Breyal

Introduction The old r-wiki optimisation challenge describes a string generation problem which I have bloged about previously both here and here. The Objective To code the most efficient algorithm, using R, to produce a sequence of strings based on a single integer input, e.g.: Solutions One Through Thirteen A ... [Read more...]

Installing Rcpp on Windows 7 for R and C++ integration

December 7, 2011 | Tony Breyal

Introduction Romain Francois presented an Rcpp solution on his blog to an old r-wiki optimisation challenge which I had also presented R solutions for previously on my blog. The Rcpp package provides a method for integrating R and C++. This allows for faster execution of an R project by recoding ... [Read more...]

outersect(): The opposite of R’s intersect() function

November 29, 2011 | Tony Breyal

The Objective To find the non-duplicated elements between two or more vectors (i.e. the ‘yellow sections of the diagram above) The Problem I needed the opposite of R’s intersect() function, an “outersect()“. The closest I found was setdiff() but the order of the input vectors produces different results, ... [Read more...]

source_https(): Sourcing an R Script from github over HTTPS

November 24, 2011 | Tony Breyal

The Objective I wanted to source R scripts hosted on my github repository for use in my blog (i.e. a github version of ?source). This would make it easier for anyone wishing to test out my code snippets on their own computers without having to manually go to my ... [Read more...]

htmlToText(): Extracting Text from HTML via XPath

November 18, 2011 | Tony Breyal

Converting HTML to plain text usually involves stripping out the HTML tags whilst preserving the most basic of formatting. I wrote a function to do this which works as follows (code can be found on github): The above uses an XPath approach to achieve it’s goal. Another approach would ... [Read more...]

fgui: Automatically Creating Widgets for Arguments of a Function – A Quick Example

November 16, 2011 | Tony Breyal

Here’s something I came across by accident, an R package called fgui which has the ability to automatically create a widget just by passing it a function with parameters, e.g.: The GUI produced from the code above looks like this: I love how easy that was to do, ...

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GScholarXScraper: Hacking the GScholarScraper function with XPath

November 13, 2011 | Tony Breyal

Kay Cichini recently wrote a word-cloud R function called GScholarScraper on his blog which when given a search string will scrape the associated search results returned by Google Scholar, across pages, and then produce a word-cloud visualisation. This was of interest to me because around the same time I posted ... [Read more...]

Web Scraping Google+ via XPath

November 11, 2011 | Tony Breyal

Google+ just opened up to allow brands, groups, and organizations to create their very own public Pages on the site. This didn’t bother me to much but I’ve been hearing a lot about Google+ lately so figured it might be fun to set up an XPath scraper to ...

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Web Scraping Yahoo Search Page via XPath

November 10, 2011 | Tony Breyal

Seeing as I’m on a bit of an XPath kick as of late, I figured I’d continue on scraping search results but this time from Yahoo.com Rolling my own version of xpathSApply to handle NULL elements seems to have done the trick and so far it’s ... [Read more...]

Facebook Graph API Explorer with R

November 10, 2011 | Tony Breyal

I wanted to play around with the Facebook Graph API using the Graph API Explorer page as a coding exercise. This facility allows one to use the API with a temporary authorisation token. Now, I don’t know how to make an R package for the proper API where you ... [Read more...]

Web Scraping Google Scholar: Part 2 (Complete Success)

November 8, 2011 | Tony Breyal

This is a followup to a post I uploaded earlier today about web scraping data off Google Scholar. In that post I was frustrated because I’m not smart enough to use xpathSApply to get the kind of results I wanted. However fast-forward to the evening whilst having dinner with ... [Read more...]

Web Scraping Google Scholar (Partial Success)

November 8, 2011 | Tony Breyal

I wanted to scrape the information returned by a Google Scholar web search into an R data frame as a quick XPath exercise. The following will successfully extract the ‘title’, ‘url’ , ‘publication’ and ‘description’. If any of these fields are not available, as in the case of a citation, the ... [Read more...]

Web Scraping Google URLs

November 7, 2011 | Tony Breyal

Google slightly changed the html code it uses for hyperlinks on search pages last Thursday, thus causing one of my scripts to stop working. Thankfully, this is easily solved in R thanks to the XML package and the power and simplicity of XPath expressions: Lovely jubbly! P.S. I know ... [Read more...]

Code Optimization: One R Problem, Eleven Solutions – Now Thirteen!

November 7, 2011 | Tony Breyal

Following up from my previous post “Code Optimisation: One R Problem, Ten Solutions – Now Eleven!” I figured out a twelfth solution after writing that blog post. Furthermore, half way through writing this blog post I figured out a thirteenth solution too. As a recap, the problem is taken from rwiki ... [Read more...]

Code Optimization: One R Problem, Ten Solutions – Now Eleven!

November 2, 2011 | Tony Breyal

Earlier this year I came across a rather interesting page about optimisation in R from rwiki. The goal was to find the most efficient code to produce strings which follow the pattern below given a single integer input n: From this we can see that the general pattern for n ... [Read more...]

Articles by Tony Breyal

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