266 search results for "pCA"

Principal Component Analysis (PCA) vs Ordinary Least Squares (OLS): A Visual Explanation

September 16, 2010
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Principal Component Analysis (PCA) vs Ordinary Least Squares (OLS): A Visual Explanation

Over at stats.stackexchange.com recently, a really interesting question was raised about principal component analysis (PCA). The gist was “Thanks to my college class I can do the math, but what does it MEAN?” I felt like this a number of times in my life. Many of my classes were focused on the technical implementations they kinda

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Using R and r.mapcalc (GRASS) to Estimate Mean Topographic Curvature

August 3, 2010
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Using R and r.mapcalc (GRASS) to Estimate Mean Topographic Curvature

Recently I was re-reading a paper on predictive soil mapping (Park et al, 2001), and considered testing one of their proposed terrain attributes in GRASS. The attribute, originally described by Blaszczynski (1997), is the distance-weighted mean differe...

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Tutorial: Principal Components Analysis (PCA) in R

May 20, 2010
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Found this tutorial by Emily Mankin on how to do principal components analysis (PCA) using R. Has a nice example with R code and several good references. The example starts by doing the PCA manually, then uses R's built in prcomp() function to do the s...

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Compcache on Ubuntu on Amazon EC2

May 4, 2010
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Compcache on Ubuntu on Amazon EC2

The following fully-automatic Bash script downloads, compiles, and initializes compcache version 0.6.2 on Ubuntu Karmic Koala (9.10). This script creates two swaps with a maximum of 4GB uncompressed size each. Two swaps are used to take advantage of 2 CPUs (or CPU cores in a multicore CPU). Compcache is a fascinating memory compression system. The

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Trying a prefmap

September 14, 2014
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Trying a prefmap

Preference mapping is a key technique in sensory and consumer research. It links the sensory perception on products to the liking of products and hence provides clues to the development of new, well tasting, products. Even though it is a key technique,...

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Mapping products in a space

September 7, 2014
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Mapping products in a space

I have read about people doing a Bayesian PCA at some points and always wondered how that would work. Then, at some point I thought of a way to do so. As ideas evolved my interest became not PCA as such, but rather in a prefmap. As a first step in that...

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Introducing H2O Lagrange (2.6.0.11) to R

September 1, 2014
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From my perspective the most important event that happened at useR! 2014 was that I got to meet the 0xdata team and now, long story short, here I am introducing the latest version of H2O, labeled Lagrange (2.6.0.11), to the R and greater data science communities. Before joining 0xdata, I was working at a competitor on a rival project and was repeatedly asked...

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Extracting Latent Variables from Rating Scales: Factor Analysis vs. Nonnegative Matrix Factorization

August 21, 2014
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Extracting Latent Variables from Rating Scales: Factor Analysis vs. Nonnegative Matrix Factorization

For many of us, factor analysis provides a gateway to learning how to run and interpret nonnegative matrix factorization (NMF). This post will analyze a set of ratings on a 218 item adjective checklist using both principal axis factor analysis and NMF....

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A Conversation with Max Kuhn – The useR! 2014 Interview

August 11, 2014
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The Interview In the video above, Max provides some amazing insights into the why and...

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Parameterized SQL queries

August 5, 2014
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Mateusz Żółtak asked me to spread the word about his new R package for parameterized SQL queries. Below you can find the copy of package vignette. If you work with SQL in R you may find it useful. Mateusz Żółtak The package RODBCext is an extension of the RODBC database connectivity package. It provides support

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