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@ -1,4 +1,10 @@
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# Abstract Algebra 2 Definitions
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---
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title: Abstract Algebra Notes
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showthedate: false
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math: true
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---
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Chapter markings are based off the book "A Book of Abstract Algebra" by Charles C. Pinter.
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## Chapter 17
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@ -2,7 +2,6 @@
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title: Algorithms Book Study
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---
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# Algorithms Book Study
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A couple of my friends and I decided to start a book club following "Algorithms" by Jeff Erickson. One bonus is that he gives it away for free on [his website](http://jeffe.cs.illinois.edu/teaching/algorithms/)!
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Of course you should totally check his book out rather than reading my notes. There are tons of witty and fun things in his textbook, not a dry reading I promise. These notes are here mostly for archival purposes.
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@ -14,4 +13,4 @@ Of course you should totally check his book out rather than reading my notes. Th
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[Chapter 3](dynamic)
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[Chapter 4](greedy)
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[Chapter 4](greedy)
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@ -1,4 +1,8 @@
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# Backtracking
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---
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title: Backtracking
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showthedate: false
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---
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This algorithm tries to construct a solution to a problem one piece at a time. Whenever the algorithm needs to decide between multiple alternatives to the part of the solution it *recursively* evaluates every option and chooses the best one.
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@ -59,4 +63,4 @@ ConstructSubset(X, i, T):
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Backtracking algorithms are used to make a *sequence of decisions*.
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When we design a new recursive backtracking algorithm, we must figure out in advance what information we will need about past decisions in the middle of the algorithm.
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When we design a new recursive backtracking algorithm, we must figure out in advance what information we will need about past decisions in the middle of the algorithm.
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@ -1,4 +1,6 @@
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# Dynamic Programming
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---
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title: Dynamic Programming
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---
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The book first goes into talking about the complexity of the Fibonacci algorithm
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@ -79,4 +81,4 @@ These algorithms are best developed in two distinct stages.
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## Greedy Algorithms
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If we're lucky we can just make decisions directly instead of solving any recursive subproblems. The problem is that greedly algorithms almost never work.
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If we're lucky we can just make decisions directly instead of solving any recursive subproblems. The problem is that greedly algorithms almost never work.
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@ -1,4 +1,7 @@
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# Greedy Algorithms
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---
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title: Greedy Algorithms
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showthedate: false
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---
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Greedy Algorithms are about making the best local choice and then blindly plowing ahead.
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The Gale-Shapley algorithm is a great greedy fit. It goes like this
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1. An arbitrary unmatched hospital A offers its position to the best doctor a who has not already rejected it.
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2. If a is unmatched, she tentatively accepts A's offer. If a already had a match but prefers A, she rejects her current match and tentatively accepts the new offer from A. Otherwise a rejects the new offer.
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2. If a is unmatched, she tentatively accepts A's offer. If a already had a match but prefers A, she rejects her current match and tentatively accepts the new offer from A. Otherwise a rejects the new offer.
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# Recursion
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---
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title: Recursion
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showthedate: false
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math: true
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---
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## Reductions
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@ -1,12 +1,8 @@
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---
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title: Bayesian Statistics
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title: Bayesian Statistics - From Concept to Data Analysis
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showthedate: false
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---
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# Bayesian Statistics: From Concept to Data Analysis
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In the Winter of 2017, I took a course on Bayesian Statistics on Coursera offered by Dr. Herbert Lee.
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Below are the notes for each of the four weeks.
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# Bayesian Statistics
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---
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title: Week 1
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showthedate: false
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math: true
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---
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## Rules of Probability
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@ -1,3 +1,9 @@
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---
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title: Week 2
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showthedate: false
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math: true
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---
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Under the frequentest paradigm, you view the data as a random sample from some larger, potentially hypothetical population. We can then make probability statements i.e, long-run frequency statements based on this larger population.
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## Coin Flip Example (Central Limit Theorem)
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@ -534,4 +540,4 @@ It may be fixed, but because we don't know what that value is, we represent our
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Frequentest confidence intervals have the interpretation that "If you were to repeat many times the process of collecting data and computing a 95% confidence interval, then on average about 95% of those intervals would contain the true parameter value; however, once you observe data and compute an interval the true value is either in the interval or it is not, but you can't tell which."
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Bayesian credible intervals have the interpretation that "Your posterior probability that the parameter is in a 95% credible interval is 95%."
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Bayesian credible intervals have the interpretation that "Your posterior probability that the parameter is in a 95% credible interval is 95%."
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@ -1,3 +1,9 @@
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---
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title: Week 3
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showthedate: false
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math: true
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---
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How do we choose a prior?
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Our prior needs to represent our personal perspective, beliefs, and our uncertainties.
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@ -406,4 +412,4 @@ After this, we need some other piece of knowledge to pin point both parameters.
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2. In Bayesian Statistics, a vague prior refers to one that's relatively flat across much of the space. For a Gamma prior we can choose $\Gamma(\epsilon, \epsilon)$ where $\epsilon$ is small and strictly positive.
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This would create a distribution with a mean of 1 and a huge standard deviation across the whole space. Hence the posterior will be largely driven by the data and very little by the prior.
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This would create a distribution with a mean of 1 and a huge standard deviation across the whole space. Hence the posterior will be largely driven by the data and very little by the prior.
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@ -1,3 +1,9 @@
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---
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title: Week 4
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showthedate: false
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math: true
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---
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## Exponential Data
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Suppose you're waiting for a bus that you think comes on average once every 10 minutes, but you're not sure exactly how often it comes.
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@ -1,4 +1,8 @@
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# Handy Quadratic Congruences Facts
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---
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title: Handy Facts about Quadratic Congruences
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showthedate: false
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math: true
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---
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## Number of Solutions
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@ -1,4 +1,8 @@
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# Real Analysis Sheet
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---
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title: Real Analysis Quick Sheet
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showthedate: false
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math: true
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---
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**Fact:** $\forall a,b, \in \mathbb{R}$, $\sqrt{ab} \le \frac{1}{2}(a + b)$.
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(b) If ($r = 0$ and $\sum{y_n} < \infty$), then $\sum{x_n} < \infty$.
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# Reproducible Research Week 1
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---
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title: Week 1
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showthedate: false
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---
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## Replication
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@ -394,4 +397,4 @@ It should tell a story
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It should not include every analysis you performed
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References should be included for statistical methods
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References should be included for statistical methods
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@ -1,3 +1,8 @@
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---
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title: Week 2
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showthedate: false
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---
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## Coding Standards for R
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1. Always use text files/text editor
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@ -1,3 +1,8 @@
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---
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title: Week 3
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showthedate: false
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---
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## tl;dr
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People are busy, especially managers and leaders. Results of data analyses are sometimes presented in oral form, but often the first cut is presented via email.
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@ -305,4 +310,4 @@ The premise of reproducible research is that with data/code available, people ca
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- Reproducible research focuses on the most "downstream" aspect of research documentation
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- Evidence-based data analysis would provide standardized best practices for given scientific areas and questions
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- Gives reviewers an important tool without dramatically increases the burden on them
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- More effort should be put into improving the quality of "upstream" aspects of scientific research
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- More effort should be put into improving the quality of "upstream" aspects of scientific research
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@ -1,3 +1,8 @@
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---
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title: Week 4
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showthedate: false
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---
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## The `cacher` Package for R
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- Add-on package for R
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@ -3,10 +3,6 @@ title: Probability and Statistical Inference
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showthedate: false
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---
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# Probability and Statistical Inference
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In the Fall of 2017, I took the course STAT 381 with Dr. Debra Hydorn. Below I included the interesting labs we worked on in the class.
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*Please note that these reports were not formatted for this site. So equations and images may not show up.*
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@ -1,6 +1,8 @@
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# Central Limit Theorem Lab
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**Brandon Rozek**
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---
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title: Central Limit Theorem
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showthedate: false
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math: true
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---
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## Introduction
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@ -1,6 +1,7 @@
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# Confidence Interval Lab
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**Written by Brandon Rozek**
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---
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title: Confidence Interval
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showthedate: false
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---
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## Introduction
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# Random Number Generation
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---
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title: Random Number Generation
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showthedate: false
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math: true
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---
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## Introduction
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# Random Walk
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---
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title: Random Walk
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showthedate: false
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math: true
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---
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## Introduction
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@ -3,7 +3,6 @@ Title: Cluster Analysis
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Description: A study of grouping observations
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---
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# Cluster Analysis
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Cluster Analysis is the art of finding inherent structures in data to form groups of similar observations. This has a myriad of applications from recommendation engines to social network analysis.
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This is an independent study, meaning that I will be studying this topic under the direction of a professor, in this case being Dr. Denhere.
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# Lecture Notes for Cluster Analysis
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---
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title: Lecture Notes for Cluster Analysis
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showthedate: false
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---
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[Lecture 1: Measures of Similarity](lec1)
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# Measures of similarity
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---
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title: Measures of similarity
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showthedate: false
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math: true
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---
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To identify clusters of observations we need to know how **close individuals are to each other** or **how far apart they are**.
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@ -328,4 +332,4 @@ Firstly, the nature of the data should strongly influence the choice of the prox
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Next, the choice of measure should depend on the scale of the data. Similarity coefficients should be used when the data is binary. For continuous data, distance of correlation-type dissimilarity measure should be used according to whether 'size' or 'shape' of the objects is of interest.
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Finally, the clustering method to be used might have some implications for the choice of the coefficient. For example, making a choice between several proximity coefficients with similar properties which are also known to be monotonically related can be avoided by employing a cluster method that depends only on the ranking of the proximities, not their absolute values.
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Finally, the clustering method to be used might have some implications for the choice of the coefficient. For example, making a choice between several proximity coefficients with similar properties which are also known to be monotonically related can be avoided by employing a cluster method that depends only on the ranking of the proximities, not their absolute values.
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# Silhouette
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---
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title: Silhouette
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showthedate: false
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math: true
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---
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This technique validates the consistency within clusters of data. It provides a succinct graphical representation of how well each object lies in its cluster.
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# Centroid-based Clustering
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---
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title: Centroid-based Clustering
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showthedate: false
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math: true
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---
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In centroid-based clustering, clusters are represented by some central vector which may or may not be a member of the dataset. In practice, the number of clusters is fixed to $k$ and the goal is to solve some sort of optimization problem.
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# Voronoi Diagram
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---
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title: Voronoi Diagram
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showthedate: false
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---
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A Voronoi diagram is a partitioning of a plan into regions based on distance to points in a specific subset of the plane.
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@ -1,4 +1,8 @@
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# K-means++
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---
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title: K-means++
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showthedate: false
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math: true
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---
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K-means++ is an algorithm for choosing the initial values or seeds for the k-means clustering algorithm. This was proposed as a way of avoiding the sometimes poor clustering found by a standard k-means algorithm.
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# K-Medoids
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---
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title: K-Medoids
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showthedate: false
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math: true
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---
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A medoid can be defined as the object of a cluster whose average dissimilarity to all the objects in the cluster is minimal.
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# K-Medians
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---
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title: K-Medians
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showthedate: false
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math: true
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---
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This is a variation of k-means clustering where instead of calculating the mean for each cluster to determine its centroid we are going to calculate the median instead.
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The algorithm is known to have converged when assignments no longer change. There is no guarantee that the optimum is found using this algorithm.
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The result depends on the initial clusters. It is common to run this multiple times with different starting conditions.
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The result depends on the initial clusters. It is common to run this multiple times with different starting conditions.
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# Introduction to Density Based Clustering
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---
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title: Introduction to Density Based Clustering
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showthedate: false
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math: true
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---
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In density-based clustering, clusters are defined as areas of higher density than the remainder of the data sets. Objects in more sparse areas are considered to be outliers or border points. This helps discover clusters of arbitrary shape.
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2. Find the connected components of *core* points on the neighborhood graph, ignoring all non-core points.
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3. Assign each non-core point to a nearby cluster if the cluster is an $\epsilon$ (eps) neighbor, otherwise assign it to noise.
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###Advantages
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### Advantages
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- Does not require one to specify the number of clusters in the data
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- Can find arbitrarily shaped clusters
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Example of Run Through
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https://www.cse.buffalo.edu/~jing/cse601/fa12/materials/clustering_density.pdf
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https://www.cse.buffalo.edu/~jing/cse601/fa12/materials/clustering_density.pdf
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@ -1,4 +1,7 @@
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# Why use different distance measures?
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---
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title: Why use different distance measures?
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showthedate: false
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---
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I made an attempt to find out in what situations people use different distance measures. Looking around in the Internet usually produces the results "It depends on the problem" or "I typically just always use Euclidean"
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@ -31,4 +34,4 @@ https://stats.stackexchange.com/questions/99171/why-is-euclidean-distance-not-a-
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Hopefully in this course, we'll discover more properties as to why it makes sense to use different distance measures since it can have a impact on how our clusters are formed.
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Hopefully in this course, we'll discover more properties as to why it makes sense to use different distance measures since it can have a impact on how our clusters are formed.
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@ -1,4 +1,8 @@
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# Principal Component Analysis Pt. 1
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---
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title: Principal Component Analysis Pt. 1
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showthedate: false
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math: true
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---
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## What is PCA?
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names(combined_list) = c("Loadings", "Components")
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return(combined_list)
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}
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```
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```
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@ -1,4 +1,8 @@
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# Revisiting Similarity Measures
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---
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title: Revisiting Similarity Measures
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showthedate: false
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math: true
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---
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## Manhatten Distance
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|
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@ -1,4 +1,8 @@
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# Cluster Tendency
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---
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title: Cluster Tendency
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showthedate: false
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math: true
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---
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This is the assessment of the suitability of clustering. Cluster Tendency determines whether the data has any inherent grouping structure.
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@ -37,4 +41,4 @@ Divide each dimension in equal width bins, and count how many points lie in each
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Do the same for the randomly sampled data
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Finally compute how much they differ using the Kullback-Leibler (KL) divergence value. If it differs greatly than we can say that the data is clusterable.
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Finally compute how much they differ using the Kullback-Leibler (KL) divergence value. If it differs greatly than we can say that the data is clusterable.
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|
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@ -1,4 +1,8 @@
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# Principal Component Analysis Part 2: Formal Theory
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---
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title: Principal Component Analysis Part 2 - Formal Theory
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showthedate: false
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||||
math: true
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---
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##Properties of PCA
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|
||||
|
@ -168,4 +172,4 @@ Principal Component Analysis is typically used in dimensionality reduction effor
|
|||
- Exclude principal components where eigenvalues are less than one.
|
||||
- Generate a Scree Plot
|
||||
- Stop when the plot goes from "steep" to "shallow"
|
||||
- Stop when it essentially becomes a straight line.
|
||||
- Stop when it essentially becomes a straight line.
|
||||
|
|
|
@ -1,4 +1,7 @@
|
|||
# Introduction to Connectivity Based Models
|
||||
---
|
||||
title: Introduction to Connectivity Based Models
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
Hierarchical algorithms combine observations to form clusters based on their distance.
|
||||
|
||||
|
@ -32,4 +35,4 @@ Or do you want to based on the farthest observations in each cluster? Farthest n
|
|||
|
||||
This method is not very robust towards outliers, which will either show up as additional clusters or even cause other clusters to merge depending on the clustering method.
|
||||
|
||||
As we go through this section, we will go into detail about the different linkage criterion and other parameters of this model.
|
||||
As we go through this section, we will go into detail about the different linkage criterion and other parameters of this model.
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Agglomerative Methods
|
||||
---
|
||||
title: Agglomerative Methods
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
## Single Linkage
|
||||
|
||||
|
@ -87,4 +91,4 @@ Since single linkage joins clusters by the shortest link between them, the techn
|
|||
|
||||
## Dendrograms
|
||||
|
||||
A **dendrogram** is a tree diagram frequently used to illustrate the arrangement of the clusters produced by hierarchical clustering. It shows how different clusters are formed at different distance groupings.
|
||||
A **dendrogram** is a tree diagram frequently used to illustrate the arrangement of the clusters produced by hierarchical clustering. It shows how different clusters are formed at different distance groupings.
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Divisive Methods Pt.1
|
||||
---
|
||||
title: Divisive Methods Pt.1
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
Divisive methods work in the opposite direction of agglomerative methods. They take one large cluster and successively splits it.
|
||||
|
||||
|
@ -39,7 +43,7 @@ This is sometimes termed *association analysis*.
|
|||
| 1 | a | b |
|
||||
| 0 | c | d |
|
||||
|
||||
####Common measures of association
|
||||
#### Common measures of association
|
||||
|
||||
$$
|
||||
|ad-bc| \tag{4.6}
|
||||
|
@ -71,4 +75,4 @@ Appealing features of monothetic divisive methods are the easy classification of
|
|||
|
||||
A further advantage of monothetic divisive methods is that it is obvious which variables produce the split at any stage of the process.
|
||||
|
||||
A disadvantage with these methods is that the possession of a particular attribute which is either rare or rarely found in combination with others may take an individual down a different path.
|
||||
A disadvantage with these methods is that the possession of a particular attribute which is either rare or rarely found in combination with others may take an individual down a different path.
|
||||
|
|
|
@ -1,4 +1,7 @@
|
|||
# Divisive Methods Pt 2.
|
||||
---
|
||||
title: Divisive Methods Pt 2.
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
Recall in the previous section that we spoke about Monothetic and Polythetic methods. Monothetic methods only looks at a single variable at a time while Polythetic looks at multiple variables simultaneously. In this section, we will speak more about polythetic divisive methods.
|
||||
|
||||
|
@ -45,4 +48,4 @@ In most methods of hierarchical clustering this is achieved by a use of an appro
|
|||
|
||||
- Any valid measure of distance measure can be used
|
||||
- In most cases, the observations themselves are not required, just hte matrix of distances
|
||||
- This can have the advantage of only having to store a distance matrix in memory as opposed to a n-dimensional matrix.
|
||||
- This can have the advantage of only having to store a distance matrix in memory as opposed to a n-dimensional matrix.
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# CURE and TSNE
|
||||
---
|
||||
title: CURE and TSNE
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
##Clustering Using Representatives (CURE)
|
||||
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Cluster Validation
|
||||
---
|
||||
title: Cluster Validation
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
There are multiple approaches to validating your cluster models
|
||||
|
||||
|
@ -69,4 +73,4 @@ Using internal evaluation metrics, you can see the impact of each point by doing
|
|||
|
||||
`clValid` contains a variety of internal validation measures.
|
||||
|
||||
Paper: https://cran.r-project.org/web/packages/clValid/vignettes/clValid.pdf
|
||||
Paper: https://cran.r-project.org/web/packages/clValid/vignettes/clValid.pdf
|
||||
|
|
|
@ -1,4 +1,7 @@
|
|||
# Readings for Lectures of Cluster Analysis
|
||||
---
|
||||
title: Readings for Independent Study of Cluster Analysis
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
## Lecture 1
|
||||
Garson Textbook Chapter 3
|
||||
|
|
|
@ -1,4 +1,7 @@
|
|||
# Cluster Analysis Spring 2018
|
||||
---
|
||||
title: Cluster Analysis
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
### Distance, Dimensionality Reduction, and Tendency
|
||||
|
||||
|
@ -116,4 +119,4 @@ The schedule above accounts for 14 weeks, so there is a week that is free as a b
|
|||
|
||||
## Conclusion
|
||||
|
||||
Creating this document got me really excited for this independent study. Feel free to give me feedback :)
|
||||
Creating this document got me really excited for this independent study. Feel free to give me feedback :)
|
||||
|
|
|
@ -1,13 +0,0 @@
|
|||
## Weekly Progress
|
||||
|
||||
I didn't do the greatest job at writing a progress report every week but here on the page are the ones I did write.
|
||||
|
||||
[January 29 2019](Jan29)
|
||||
|
||||
[February 12 2019](Feb12)
|
||||
|
||||
[February 25 2019](Feb25)
|
||||
|
||||
[March 26 2019](Mar26)
|
||||
|
||||
[April 2 2019](Apr2)
|
|
@ -1,4 +1,7 @@
|
|||
# Progress Report for Week of April 2nd
|
||||
---
|
||||
title: Progress Report for Week of April 2nd
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
## Added Video Recording Capability to MinAtar environment
|
||||
|
||||
|
@ -20,6 +23,3 @@ Playing around with the ideas of autoencoders, I wanted a way to discretized my
|
|||
|
||||
I'll probably look towards implementing what the paper did for my library and move on to a different piece.
|
||||
|
||||
|
||||
|
||||
Guru Indian: 3140 Cowan Blvd, Fredericksburg, VA 22401
|
|
@ -1,4 +1,8 @@
|
|||
# Weekly Progress Feb 12
|
||||
---
|
||||
title: Weekly Progress Feb 12
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
## Finished writing scripts for data collection
|
||||
|
||||
|
@ -60,4 +64,4 @@ The two parameters I use schedulers in normally are:
|
|||
|
||||
Jimmy Lei Ba, Jamie Ryan Kiros, Geoffrey E. Hinton. **Layer Normalization.**
|
||||
|
||||
It's nicely implemented in PyTorch already so I threw that in for each layer of the network. Reduces the average loss.
|
||||
It's nicely implemented in PyTorch already so I threw that in for each layer of the network. Reduces the average loss.
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Weekly Progress for February 25th
|
||||
---
|
||||
title: Weekly Progress for February 25th
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
## Evolutionary Algorithms
|
||||
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Weekly Progress Jan 29
|
||||
---
|
||||
title: Weekly Progress Jan 29
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
## 1. Training From Demonstrations
|
||||
|
||||
|
@ -6,13 +10,13 @@ Training from demonstrations is the act of using previous data to help speed up
|
|||
|
||||
I read two papers on the topic:
|
||||
|
||||
[1] Gabriel V. de la Cruz Jr., Yunshu Du, Matthew E. Taylor. **Pre-training Neural Networks with Human Demonstrations for Deep Reinforcement Learning**.
|
||||
(1) Gabriel V. de la Cruz Jr., Yunshu Du, Matthew E. Taylor. **Pre-training Neural Networks with Human Demonstrations for Deep Reinforcement Learning**.
|
||||
|
||||
https://arxiv.org/abs/1709.04083
|
||||
|
||||
The authors showed how you can speed up the training of a DQN network, especially under problems involving computer vision, if you first train the convolution layers by using a supervised loss between the actions the network would choose and the actions from the demonstration data given a state.
|
||||
|
||||
[2] Todd Hester, Matej Vecerik, Olivier Pietquin, Marc Lanctot, Tom Schaul, Bilal Piot, Dan Horgan, John Quan, Andrew Sendonaris, Gabriel Dulac-Arnold, Ian Osband, John Agapiou, Joel Z. Leibo, Audrunas Gruslys. **Deep Q-learning from Demonstrations.**
|
||||
(2) Todd Hester, Matej Vecerik, Olivier Pietquin, Marc Lanctot, Tom Schaul, Bilal Piot, Dan Horgan, John Quan, Andrew Sendonaris, Gabriel Dulac-Arnold, Ian Osband, John Agapiou, Joel Z. Leibo, Audrunas Gruslys. **Deep Q-learning from Demonstrations.**
|
||||
|
||||
https://arxiv.org/abs/1704.03732
|
||||
|
||||
|
@ -32,9 +36,9 @@ The intuition behind this is that for the loss to be zero, the network would've
|
|||
|
||||
The main environment I chose to test these algorithms is Acrobot. It is a control theory problem and it has several physics related numbers as input. (Not image based)
|
||||
|
||||
I noticed when implementing [1] at least for the non-convolution case, there's no point in trying to train earlier layers. Perhaps I'll try again when I move onto the atari gameplays...
|
||||
I noticed when implementing (1) at least for the non-convolution case, there's no point in trying to train earlier layers. Perhaps I'll try again when I move onto the atari gameplays...
|
||||
|
||||
I decided against following [2] exactly. It's not that I disagree with the approach, but I don't like the need for "expert" data. If you decide to proceed anyways with non-expert data, you need to remember that it is incorporated into the loss function. Which means that you fall risk into learning sub-optimal policies.
|
||||
I decided against following (2) exactly. It's not that I disagree with the approach, but I don't like the need for "expert" data. If you decide to proceed anyways with non-expert data, you need to remember that it is incorporated into the loss function. Which means that you fall risk into learning sub-optimal policies.
|
||||
|
||||
In the end, what I decided to do was the following
|
||||
|
||||
|
@ -62,4 +66,4 @@ In our case, the $\mu$ would be the typical weights and biases, and the $\sigma$
|
|||
|
||||
The concept is that as the network grows more confident about it's predictions, the variation in the weights start to decrease. This way the exploration is systematic and not something randomly injected like the epsilon-greedy strategy.
|
||||
|
||||
The paper describes replacing all your linear densely connected layers with this noisy linear approach.
|
||||
The paper describes replacing all your linear densely connected layers with this noisy linear approach.
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Progress for Week of March 26
|
||||
---
|
||||
title: Progress for Week of March 26
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
## Parallelized Evolutionary Strategies
|
||||
|
||||
|
@ -8,4 +12,4 @@ When the parallel ES class is declared, I start a pool of workers that then gets
|
|||
|
||||
I started looking through papers on Exploration and am interested in using the theoretical niceness of Count-based exploration in tabular settings and being able to see their affects in the non-tabular case.
|
||||
|
||||
""[Unifying Count-Based Exploration and Intrinsic Motivation](https://arxiv.org/abs/1606.01868)" creates a model of a arbitrary density model that follows a couple nice properties we would expect of probabilities. Namely, $P(S) = N(S) / n$ and $P'(S) = (N(S) + 1) / (n + 1)$. Where $N(S)$ represents the number of times you've seen that state, $n$ represents the total number of states you've seen, and $P'(S)$ represents the $P(S)$ after you have seen $S$ another time. With this model, we are able to solve for $N(S)$ and derive what the authors call a *Psuedo-Count*.
|
||||
""[Unifying Count-Based Exploration and Intrinsic Motivation](https://arxiv.org/abs/1606.01868)" creates a model of a arbitrary density model that follows a couple nice properties we would expect of probabilities. Namely, $P(S) = N(S) / n$ and $P'(S) = (N(S) + 1) / (n + 1)$. Where $N(S)$ represents the number of times you've seen that state, $n$ represents the total number of states you've seen, and $P'(S)$ represents the $P(S)$ after you have seen $S$ another time. With this model, we are able to solve for $N(S)$ and derive what the authors call a *Psuedo-Count*.
|
||||
|
|
|
@ -0,0 +1,16 @@
|
|||
---
|
||||
title: Weekly Progress
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
I didn't do the greatest job at writing a progress report every week but here on the page are the ones I did write.
|
||||
|
||||
[January 29 2019](jan29)
|
||||
|
||||
[February 12 2019](feb12)
|
||||
|
||||
[February 25 2019](feb25)
|
||||
|
||||
[March 26 2019](mar26)
|
||||
|
||||
[April 2 2019](apr2)
|
|
@ -1,4 +1,5 @@
|
|||
---
|
||||
title: Abstract
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
|
@ -12,4 +13,4 @@ QEP: The Q-Value Policy Evaluation Algorithm
|
|||
|
||||
|
||||
|
||||
*Abstract.* In Reinforcement Learning, sample complexity is often one of many concerns when designing algorithms. This concern outlines the number of interactions with a given environment that an agent needs in order to effectively learn a task. The Reinforcement Learning framework consists of finding a function (the policy) that maps states/scenarios to actions while maximizing the amount of reward from the environment. For example in video games, the reward is often characterized by some score. In recent years a variety of algorithms came out falling under the categories of Value-based methods and Policy-based methods. Value-based methods create a policy by approximating how much reward an agent is expected to receive if it performs the best actions from a given state. It is then common to choose the actions that maximizes such values. Meanwhile, in Policy-based methods, the policy function produces probabilities that an agent performs each action given a state and this is then optimized for the maximum reward. As such, Value-based methods produce deterministic policies while policy-based methods produce stochastic/probabilistic policies. Empirically, Value-based methods have lower sample complexity than Policy-based methods. However, in decision making not every situation has a best action associated with it. This is mainly due to the fact that real world environments are dynamic in nature and have confounding variables affecting the result. The QEP Algorithm combines both the Policy-based methods and Value-based methods by changing the policy's optimization scheme to involve approximate value functions. We have shown that this combines the benefits of both methods so that the sample complexity is kept low while maintaining a stochastic policy.
|
||||
*Abstract.* In Reinforcement Learning, sample complexity is often one of many concerns when designing algorithms. This concern outlines the number of interactions with a given environment that an agent needs in order to effectively learn a task. The Reinforcement Learning framework consists of finding a function (the policy) that maps states/scenarios to actions while maximizing the amount of reward from the environment. For example in video games, the reward is often characterized by some score. In recent years a variety of algorithms came out falling under the categories of Value-based methods and Policy-based methods. Value-based methods create a policy by approximating how much reward an agent is expected to receive if it performs the best actions from a given state. It is then common to choose the actions that maximizes such values. Meanwhile, in Policy-based methods, the policy function produces probabilities that an agent performs each action given a state and this is then optimized for the maximum reward. As such, Value-based methods produce deterministic policies while policy-based methods produce stochastic/probabilistic policies. Empirically, Value-based methods have lower sample complexity than Policy-based methods. However, in decision making not every situation has a best action associated with it. This is mainly due to the fact that real world environments are dynamic in nature and have confounding variables affecting the result. The QEP Algorithm combines both the Policy-based methods and Value-based methods by changing the policy's optimization scheme to involve approximate value functions. We have shown that this combines the benefits of both methods so that the sample complexity is kept low while maintaining a stochastic policy.
|
||||
|
|
|
@ -3,7 +3,6 @@ Title: Reinforcement Learning
|
|||
Description: The study of optimally mapping situations to actions
|
||||
---
|
||||
|
||||
# Reinforcement Learning
|
||||
Reinforcement learning is the art of analyzing situations and mapping them to actions in order to maximize a numerical reward signal.
|
||||
|
||||
In this independent study, I as well as Dr. Stephen Davies, will explore the Reinforcement Learning problem and its subproblems. We will go over the bandit problem, markov decision processes, and discover how best to translate a problem in order to **make decisions**.
|
||||
|
@ -38,8 +37,6 @@ Code will occasionally be written to solidify the learning material and to act a
|
|||
|
||||
[Github Link](https://github.com/brandon-rozek/ReinforcementLearning)
|
||||
|
||||
Specifically, if you want to see agents I've created to solve some OpenAI environments, take a look at this specific folder in the Github Repository
|
||||
|
||||
[Github Link](https://github.com/Brandon-Rozek/ReinforcementLearning/tree/master/agents)
|
||||
Specifically, if you want to see agents I've created to solve some OpenAI environments, take a look at this specific folder in the Github Repository. [Github Link](https://github.com/Brandon-Rozek/ReinforcementLearning/tree/master/agents)
|
||||
|
||||
|
||||
|
|
|
@ -1,4 +1,7 @@
|
|||
# Lecture Notes for Reinforcement Learning
|
||||
---
|
||||
title: Lecture Notes for Reinforcement Learning
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
[Chapter 1: An Introduction](intro)
|
||||
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Chapter 2: Multi-armed Bandits
|
||||
---
|
||||
title: Chapter 2 - Multi-armed Bandits
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
Reinforcement learning *evaluates* the actions taken rather than accepting $instructions$ of the correct actions. This creates the need for active exploration.
|
||||
|
||||
|
@ -141,4 +145,4 @@ This is an example of an *associative search* task, so called because it involve
|
|||
|
||||
If actions are allowed to affect the next situation as well as the reward, then we have the full reinforcement learning problem. This will be presented in the next chapter of the book with its ramifications appearing throughout the rest of the book.
|
||||
|
||||
![1536321791927](/home/rozek/Pictures/1536321791927.png)
|
||||
![1536321791927](/home/rozek/Pictures/1536321791927.png)
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Chapter 4: Dynamic Programming
|
||||
---
|
||||
title: Chapter 4 - Dynamic Programming
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
Dynamic programming refers to a collection of algorithms that can be used to compute optimal policies given a perfect model of the environment as a Markov decision process (MDP).
|
||||
|
||||
|
|
|
@ -1,4 +1,7 @@
|
|||
# Introduction to Reinforcement Learning Day 1
|
||||
---
|
||||
title: Introduction to Reinforcement Learning Day 1
|
||||
showthedate: false
|
||||
---
|
||||
|
||||
Recall that this course is based on the book --
|
||||
|
||||
|
@ -63,4 +66,4 @@ Most of the time in a reinforcement learning algorithm, we move greedily, select
|
|||
|
||||
|
||||
|
||||
Summary: Reinforcement learning is learning by an agent from direct interaction wit its environment, without relying on exemplary supervision or complete models of the environment.
|
||||
Summary: Reinforcement learning is learning by an agent from direct interaction wit its environment, without relying on exemplary supervision or complete models of the environment.
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Chapter 5: Monte Carlo Methods
|
||||
---
|
||||
title: Chapter 5 - Monte Carlo Methods
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
Monte Carlo methods do not assume complete knowledge of the environment. They require only *experience* which is a sample sequence of states, actions, and rewards from actual or simulated interaction with an environment.
|
||||
|
||||
|
|
|
@ -1,4 +1,8 @@
|
|||
# Chapter 3: Finite Markov Decision Processes
|
||||
---
|
||||
title: Chapter 3 - Finite Markov Decision Processes
|
||||
showthedate: false
|
||||
math: true
|
||||
---
|
||||
|
||||
Markov Decision processes are a classical formalization of sequential decision making, where actions influence not just immediate rewards, but also subsequent situations, or states, and through those future rewards. Thus MDPs involve delayed reward and the need to trade-off immediate and delayed reward. Whereas in bandit problems we estimated the value of $q_*(a)$ of each action $a$, in MDPs we estimate the value of $q_*(s, a)$ of each action $a$ in state $s$.
|
||||
|
||||
|
|
Loading…
Reference in a new issue