Machine Learning Study Group – Week 2 & 3 Recap

Hello World,

So this is another recap from our study group covering the Andrew NG course on Coursera. Lets start by a quick summary from the two weeks. Week 1 was all about introduction to linear regression and gradient descent. There were no assignments due. Week 3 was all about multi-variate linear regression, normalization and a few other topics. There was a coding assignment as well as a quiz due for week 2.
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Feature Scaling & Machine Learning

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If you are practicing machine learning, you are likely going to run into this at some point.  Basically the reason we use feature scaling is to help our algorithms train faster and better.  Lets begin by taking a standard theta optimization equation to help better understand the problem.
\theta_j = \theta_j - \alpha \cdot \frac{ \sum_i^m \left(H_{\theta}\left(x\right) - y\right) \cdot x_j } { m }

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Linear Regression from Scratch using Linear Algebra

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So I wrote an article earlier “Linear Regression From Scratch”.  Many folks have pointed out that this is in fact not the optimal approach.  Now being the perfectionist I decided to re-implement.  Not to mention it works great in my own libraries.  The following article discussing converting the original code into code that uses linear algebra.  Beyond this, it still works in PCL for xamarin,  Hoo-Rah Xamarin!

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Machine Learning Study Group Recap – Week 1

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So many of you who are here are probably part of the study group.  For those who are not or are perhaps referencing this at a later time, this is in regards to the following course on Coursera. If you would like to join our study group, please see one of the following meetup pages: Fort Lauderdale Machine Learning or Florida Dot Net.

Here in South Florida we have a strong Machine Learning and Data Science community and therefor it is easy to get a study group together.  This article is a recap from the first meeting of our study group.  Note that this first meeting is the week before the class started.  Therefor this article is a great introduction to machine learning, languages, commitments and more generally applicable questions and concerns.

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Linear Regression from Scratch

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So today we will do a quick conversion from mathematical notations of Algebra into a real algorithm that can be executed.  Note we will not be covering gradient descent, but rather only cost functions, errors and execution of these to provide the framework for gradient descent.  Gradient descent has so many flavors that it deserves its own article.

So to the mathematical representation.

LinearRegression

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Intro to R Data Structures

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This article is a video tutorial on introduction to the very bare basics of R.  Its a bit dry, but it is the underlying components of everything covered in the interesting stuff.  Can’t do cool stuff without understanding the basics first.

Part 1: Introduction to Microsoft R Open.

Part 2: Introduction to R Data Structures

Part 3: Data Manipulation with R

Part 4: Beautiful Visualizations with R

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