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This tutorial will enable anyone with some programming experience to begin analyzing data with the R programming language
by Jeremy Howard and Mike Bowles
When doing predictive modelling, there are two situations in which you might find yourself:
You need to fit a well-defined parameterised model to your data, so you require a learning algorithm which can find those parameters on a large data set without over-fitting
You just need a “black box” which can predict your dependent variable as accurately as possible, so you need a learning algorithm which can automatically identify the structure, interactions, and relationships in the data
For case (1), lasso and elastic-net regularized generalized linear models are a set of modern algorithms which meet all these needs. They are fast, work on huge data sets, and avoid over-fitting automatically. They are available in the “glmnet” package in R.
For case (2), ensembles of decision trees (often known as “Random Forests”) have been the most successful general-purpose algorithm in modern times. For instance, most Kaggle competitions have at least one top entry that heavily uses this approach. This algorithm is very simple to understand, and is fast and easy to apply. It is available in the “randomForest” package in R.
Mike and Jeremy will explain in simple terms, using no complex math, how these algorithms work, and will also explain using numerous examples how to apply them using R. They will also provide advice on how to select from these algorithms, and will show how to prepare the data, and how to use the trained models in practice.
Rhadoop is an open source project spearheaded by Revolution Analytics to grant data scientists access to Hadoop’s scalability from their favorite language, R. RHadoop is comprised of three packages.
rmr allows R developers to program in the mapreduce framework, and to all developers provides an alternative way to implement mapreduce programs that strikes a delicate compromise betwen power and usability. It allows to write general mapreduce programs, offering the full power and ecosystem of an existing, established programming language. It doesn’t force you to replace the R interpreter with a special run-time—it is just a library. You can write logistic regression in half a page and even understand it. It feels and behaves almost like the usual R iteration and aggregation primitives. It is comprised of a handful of functions with a modest number of arguments and sensible defaults that combine in many useful ways. But there is no way to prove that an API works: one can only show examples of what it allows to do and we will do that covering a few from machine learning and statistics. Finally, we will discuss how to get involved.
Data isn’t just for supporting decisions and creating actionable interfaces. Data can create nuance, giving new understandings that lead to further questioning—rather than just actionable decisions. In particular, curiosity, and creative thinking can be driven by combining different data sets and techniques to develop a narrative around a set of data sets that tells the story of a place—the emotions, history, and change embedded in the experience of the place.
In this session, we’ll see how far we can go in exploring one street in San Francisco, Haight Street, and see how well we can understand it’s geography, ebbs and flows, and behavior by combining as many data sources as possible. We’ll integrate basic public data from the city, street and mapping data from Open Street Maps, real estate and rental listings data, data from social services like Foursquare, Yelp and Instagram, and analyze photographs of streets from mapping services to create a holistic view of one street and see what we can understand from this. We’ll show how you can summarize this data numerically, textually, and visually, using a number of simple techniques.
We’ll cover how traditional data analysis tools like R and NumPy can be combined with tools more often associated with robotics like OpenCV (computer-vision) to create a more complete data set. We’ll also cover how traditional data visualization techniques can be combined with mapping and augmented reality to present a more complete picture of any place, including Haight Street.
28th February to 1st March 2012