261 search results for "PCA"

R et Twitter

April 22, 2013
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R et Twitter

(This article was first published on Learning Data Science , and kindly contributed to R-bloggers) On va dans ce post, illustrer une utilisation simple des packages twitteR, StreamR, tm qui permettent faire du textmining. En réalité, les deux premiers permettent de récuperer les tweets et de faire des comptages simples et complexes et le dernier permet de faire du...

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Using the SVD to find the needle in the haystack

April 19, 2013
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Using the SVD to find the needle in the haystack

Sitting with a data set with too many variables? The SVD can be a valuable...

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Reconstructing Principal Component Analysis Matrix

April 5, 2013
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Reconstructing Principal Component Analysis Matrix

PCA is widely used method for finding patterns in high-dimensional data. Whether you use it to compress large matrix or to remove one of the principal components in biological datasets, you’ll end up with the task of performing series of … Continue reading →

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Veterinary Epidemiologic Research: GLM (part 4) – Exact and Conditional Logistic Regressions

March 22, 2013
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Veterinary Epidemiologic Research: GLM (part 4) – Exact and Conditional Logistic Regressions

Next topic on logistic regression: the exact and the conditional logistic regressions. Exact logistic regression When the dataset is very small or severely unbalanced, maximum likelihood estimates of coefficients may be biased. An alternative is to use exact logistic regression, available in R with the elrm package. Its syntax is based on an events/trials formulation.

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Violin plots and regional income distribution

March 20, 2013
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Violin plots and regional income distribution

While preparing my slides for statistical graphics, a plot really caught my eye when I was playing around with the data. I started off by plotting the time seriesof GNI per capita by country, and as expected it got quite messy and...

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Samsung Phone Data Analysis Project

March 19, 2013
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Samsung Phone Data Analysis Project

Below are my findings from the second data analysis project in Dr. Jeffery Leek’s John Hopkins Coursera class. Introduction I used the  “Human Activity Recognition Using Smartphones Dataset” (UCI, 2013) to build a model. This data  was recorded from a Samsung prototype smartphone with a built-in accelerometer. The purpose of my model was to recognize the type

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Evaluation of Orthogonal Signal Correction for PLS modeling (OSC-PLS and OPLS)

March 15, 2013
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Evaluation of Orthogonal Signal Correction for PLS modeling (OSC-PLS and OPLS)

Partial least squares projection to latent structures or PLS is one of my favorite modeling algorithms. PLS is an optimal algorithm for predictive modeling using wide data or data with  rows << variables. While there is s a wealth of literature regarding the application of PLS to various tasks, I find it especially useful for biological

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Using maps and ggplot2 to visualize college hockey championships

March 13, 2013
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Using maps and ggplot2 to visualize college hockey championships

Short: I plot the frequency of college hockey championships by state using the maps package, and ggplot2 Note: this example is based heavily on the example provided athttp://www.dataincolour.com/2011/07/maps-with-ggplot2/ data reference:http://en.wikipedia.org/wiki/NCAA_Men%27s_Ice_Hockey_Championship Question of interestAs a good Minnesotan, I've believed for quite some time that the colder, Northern states enjoy a competitive advantage when it...

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reading raster data using library(parallel)

March 3, 2013
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reading raster data using library(parallel)

Recently, I have been doing some analysis for a project I am involved in. In particular, I was interested what role pacific sea surface temperatures play with regard to rainfall in East Africa. I spare you the details as I … Continue reading →

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Shading and Points with xtsExtra plot.xts

February 28, 2013
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Shading and Points with xtsExtra plot.xts

For some reason, I feel like have much better control with plot.xts function from the xtsExtra package described here over some of the other more refined R graphical packages. Maybe, it is just my simple mind, but recently I wanted to shade holding per...

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