Category: R

Not Catching Them All

Published 2016-08-23 by Kevin Feasel

Hanjo Odendaal explains clustering techniques using Pokemon:

To collect the data on all the first generation pokemon, I employ Hadley Wickam’s rvest package. I find it very intuitive and can handle all of my needs in collecting and extracting the data from a pokemon wiki. I will grab all the Pokemon up until to Gen II, which constitutes 251 individuals. I did find the website structure a bit of a pain as each pokemon had very different looking web pages. But, with some manual hacking, I eventually got the data in a nice format.

This probably means a lot more to you if you grew up in front of a Game Boy, but there’s some good technique in here regardless.

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Visualizations In Five Lines Of Code

Published 2016-08-23 by Kevin Feasel

David Smith highlights a Sharon Machlis article showing visualizations in up to five lines of R code:

I’ve reproduced Sharon’s code and charts below. I did make a couple of tweaks to the code, though. I added a call to checkpoint(“2016-08-22”) which, if you’ve saved the code to a file, will install all the necessary packages for you. (I also verified that the code runs with package versions as of today’s date, and if you’re trying out this code at a later time it will continue to do so, thanks to checkpoint.) I also modified the data download code to make it work more easily on Windows. Here are the charts and code

It’s really easy to get basic visualizations within R, and these are better than basic visualizations.

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Resource Governor For R

Published 2016-08-19 by Kevin Feasel

Tomaz Kastrun describes using Resource Governor with Microsoft R Services:

Setting external resource pool for execution of R commands using sp_execute_external_script has proven extremely useful, especially in cases where you have other workers present, when you don’t want to overdo on data analysis and get to much resources from others (especially when running data analysis in production environment) or when you know that your data analysis will require maximum CPU and memory for a specific period. In such cases using and definingexternal resource pool is not only useful but highly recommended.

Resource governor is a feature that enables you to manage SQL Server workload and system resource consumption their limits. Limits can be configures for any workload in terms of CPU, Memory and I/O consumption. Where you have many different workloads on the same SQL Server, resource Governor helps allocate requested resources.

If you’re concerned about R soaking up all of your server’s memory, Resource Governor is a great way of limiting that risk.

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R Or M?

Published 2016-08-17 by Kevin Feasel

Ryan Wade gives a few scenarios in which R might be a better language choice than M for Power BI integration:

When referring to what can be done in iOS, Apple often say that there is an “app” for that. Likewise, when R developers refer to what can be done in R, we often say that there is a “package” for that. For instance:

· If one needs to scrap data from the web there are packages for that (rvest, rcurl, and others)

· If one needs to make complicated transformations to their data there are packages for that (dplyr, tidyr, lubrdiate, stringr, and others)

I like the F#-ness of M, but I admit that I’m happy there’s some fairly close R integration within Power BI, as that means there’s one fewer language I need to learn right now…

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Analytic Tool Usage

Published 2016-08-16 by Kevin Feasel

Alex Woodie notes the increased popularity of Python for data analysis:

According to the results of the 2016 survey, R is the preferred tool for 42% of analytics professionals, followed by SAS at 39% and Python at 20%. While Python’s placing may at first appear to relegate the language to Bronze Medal status, it’s the delta here that really matters.

It’s interesting to see the breakdowns of who uses which language, comparing across industry, education, work experience, and geographic lines.

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Missing Libraries With SQL Server R Services

Published 2016-08-15 by Kevin Feasel

Tomaz Kastrun has a script to check and install missing packages in SQL Server R Services code:

Result in this case will be successful with correct R results and sp_execute_external_script will not return error for missing libraries.

I added a “fake” library called test123 for testing purposes if all the libraries will be installed successfully.

At the end the script generated xp_cmdshell command (in one line)

This is a rather clever solution to a problem which I’d rather not exist. There really ought to be a better way for authorized users programmatically to install packages.

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Using Focus() On Correlations

Published 2016-08-11 by Kevin Feasel

Simon Jackson explains how to use the focus() function in R to narrow down a data frame of correlation coefficients based on a subset of variables:

focus() works similarly to select() from the dplyr package (which is loaded along with the corrr package). You add the names of the columns you wish to keep in your correlation data frame. Extending select(), focus()will then remove the remaining column variables from the rows. This is whympg does not appear in the rows above. Here’s another example with two variables:

Click through for the entire article.

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Understanding Bookmakers’ Odds Using R

Published 2016-08-11 by Kevin Feasel

Andrew Collier looks at odds, vigs, and other bookmaking concepts through the lens of the R programming language:

The house edge is 2.70%. On average a gambler would lose 2.7% of his stake per game. Of course, on any one game he would either win or lose, but this is the long term expectation. Another way of looking at this is to say that the Return To Player (RTP) is 97.3%, which means that on average a gambler would get back 97.3% of his stake on every game.

Below are the results of a simulation of 100 gamblers betting on even numbers. Each starts with an initial capital of 100. The red line represents the average for the cohort. After 1000 games two gamblers have lost all of their money. Of the remaining 98 players, only 24 have made money while the rest have lost some portion of their initial capital.

This is a very interesting article if you’re interested in basic statistics. 13-year-old Onion article of note.

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Microsoft R Server On Spark

Published 2016-08-10 by Kevin Feasel

Max Kaznady, et al, discuss using Microsoft R Server on Spark to perform rapid prototyping against the NYC Taxi dataset:

Once the cluster is created, you can connect to the edge node where MRS is already pre-installed by SSHing to r-server.YOURCLUSTERNAME-ssh.azurehdinsight.net with the credentials which you supplied during the cluster creation process. In order to do this in MobaXterm, you can go to Sessions, then New Sessions and then SSH.

The default installation of HDI Spark on Linux cluster does not come with RStudio Server installed on the edge node. RStudio Server is a popular open source integrated development environment (IDE) available for R that provides a browser-based IDE for use by remote clients. This tool allows you to benefit from all the power of R, Spark and Microsoft HDInsight cluster through your browser. In order to install RStudio you can follow the steps detailed in the guide, which reduces to running a script on the edge node.

If you’ve been meaning to get further into Spark & R, this is a great article to follow along with on your own.

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Quality Graphics With R

Published 2016-08-09 by Kevin Feasel

David Smith discusses building high-quality visuals with R:

Note the use of an attractive colour pallette, style-compatible fonts, and even the official Olympic icons for the sports. I just took a screenshot here, but if you click through to the actual site you’ll notice that these graphics are also scale-independent (you can zoom in on your browser and they’ll look better, not worse) and even interactive (pop-ups appear with country-specific data when you hover over a bar).

Duc-Quang has been generous enough to provide the R code behind these charts if you’d like to try your hand at something similar. The data themselves were scraped from the official Rio 2016 site. The bar charts were created using a standard geom_bar plot using ggplot2, with a custom theme to set the font to OpenSans Condensed. The interactive elements were added using the ggiraph package and the geom_bar_interactive function. The chart titles (including the icons) were created as HTML headers directly, which was then exported along with the interactive charts using the save_html function.

I’m impressed that this all comes from R. There’s a good bit of work involved in getting this going, but you can get professional-grade graphics quality with R, and that’s pretty cool.

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