282 search results for "PCA"

PCA file calculation with "R".

December 5, 2011
By
PCA file calculation with "R".

X es la matriz centrada (X is the centered matrix). Xcov es la matriz de covarianzas de X (Xcov is the covariance matrix of X).Con la función "eigen" calculamos los "eigenvectors" y "eigenvalues" de Xcov.(With the function "eigen" we calculate the "ei...

Read more »

Big-Data PCA: 50 years of stock data

June 17, 2011
By
Big-Data PCA: 50 years of stock data

In this post, Revolution engineer Sherry LaMonica shows us how to use the RevoScaleR big-data package in Revolution R Enterprise to do principal components analysis on 50 years of stock market data -- ed. Principal components analysis, or PCA, seeks to find a set of orthogonal axes such that the first axis, or first principal component, accounts for as...

Read more »

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

September 16, 2010
By
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

Read more »

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

August 3, 2010
By
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...

Read more »

Tutorial: Principal Components Analysis (PCA) in R

May 20, 2010
By

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...

Read more »

Compcache on Ubuntu on Amazon EC2

May 4, 2010
By
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

Read more »

Growing some Trees

March 18, 2015
By
Growing some Trees

Consider here the dataset used in a previous post, about visualising a classification (with more than 2 features), > MYOCARDE=read.table( + "http://freakonometrics.free.fr/saporta.csv", + header=TRUE,sep=";") The default classification tree is > arbre = rpart(factor(PRONO)~.,data=MYOCARDE) > rpart.plot(arbre,type=4,extra=6) We can change the options here, such as the minimum number of observations, per node > arbre = rpart(factor(PRONO)~.,data=MYOCARDE, + control=rpart.control(minsplit=10)) > rpart.plot(arbre,type=4,extra=6) or...

Read more »

How to Make a Histogram with ggplot2

March 12, 2015
By
How to Make a Histogram with ggplot2

In our previous post you learned how to make histograms with the hist() function. You can also make a histogram with ggplot2, “a plotting system for R, based on the grammar of graphics”. This post will focus on making a Histogram With ggplot2. Want to learn more? Discover the DataCamp tutorials. Step One. Check That The post

Read more »

Visualising a Classification in High Dimension

March 6, 2015
By
Visualising a Classification in High Dimension

So far, when discussing classification, we’ve been playing on my toy-dataset (actually, I should no claim it’s mine, it is inspired by the one used in the introduction of Boosting, by Robert Schapire and Yoav Freund). But in ral life, there are more observations, and more explanatory variables.With more than two explanatory variables, it starts to be more complicated...

Read more »

Getting a statistics education: Review of the MSc in Statistics (Sheffield)

February 14, 2015
By
Getting a statistics education: Review of the MSc in Statistics (Sheffield)

Some background:I started using statistics for my research sometime in 1999 or 2000. I was a student at Ohio State, Linguistics, and I had just gotten interested in psycholinguistics. I knew almost nothing ...

Read more »