Blog Archives

Creating Pretty Documents with the prettydoc Package

August 10, 2016
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Creating Pretty Documents with the prettydoc Package

Have you ever tried to find a lightweight yet nice theme for the R Markdown documents, like this page? Themes for R Markdown With the powerful rmarkdown package, we could easily create nice HTML document by adding some meta information in the he...

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recosystem: Recommender System Using Parallel Matrix Factorization

July 14, 2016
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recosystem: Recommender System Using Parallel Matrix Factorization

A Quick View of Recommender System The main task of recommender system is to predict unknown entries in the rating matrix based on observed values, as is shown in the table below: Each cell with number in it is the rating given by some user on a specific item, while those marked with question marks are unknown ratings that need to be...

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RcppNumerical: Numerical integration and optimization with Rcpp

April 8, 2016
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RcppNumerical: Numerical integration and optimization with Rcpp

Introduction I have seen several conversations in Rcpp-devel mailing list asking how to compute numerical integration or optimization in Rcpp. While R in fact has the functions Rdqags, Rdqagi, nmmin, vmmin etc. in its API to accomplish such tasks, it is not so straightforward to use them with Rcpp. For my own research projects I need to do a lot of numerical integration, root finding...

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Large scale eigenvalue decomposition and SVD with rARPACK

February 21, 2016
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In January 2016, I was honored to receive an “Honorable Mention” of the John Chambers Award 2016. This article was written for R-bloggers, whose builder, Tal Galili, kindly invited me to write an introduction to the rARPACK package. A Short Story of rARPACK Eigenvalue decomposition is a commonly used technique in numerous statistical problems. For example, principal component analysis (PCA) basically conducts eigenvalue decomposition on...

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Using showtext in knitr

July 20, 2014
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Using showtext in knitr

Thanks to the issue report by yufree and Yihui’s kind work, from version 1.6.10 (development version), knitr starts to support using showtext to change fonts in R plots. To demonstrate its usage, this document itself serves as an example. (Rmd source code) We first do some setup work, mainly about setting options that control the appearance of the plots. Notice that if you create plots in PNG format...

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Introduction to dynamic document and knitr

April 2, 2014
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Today I gave a presentation for GSO(Graduate Student Organization) of our department, mainly about the idea of dynamic document and its implementation using knitr. Here are the slides I showed in the talk, written with Markdown and knitr.

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Using system fonts in R graphs

December 31, 2013
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Using system fonts in R graphs

This is a pretty old topic in R graphics. A classical article in R NEWS, Non-standard fonts in PostScript and PDF graphics, describes how to use and embed system fonts in the PDF/PostScript device. More recently, Winston Chang developed the extrafont package, which makes the procedure much easier. A useful introduction article can be found in the readme page of extrafont, and also from the Revolution blog. Now,...

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A Conversation with Hadley Wickham

September 26, 2013
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A Conversation with Hadley Wickham

Dr. Hadley Wickham is the Chief Scientist of RStudio and Assistant Professor of Statistics at Rice University. He is the developer of the famous R package ggplot2 for data visualization and the author of many other widely used packages like plyr and reshape2. On Sep 13, 2013 he gave a talk at Department of Statistics, Purdue University, and later I (Yixuan)...

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Handwriting recognition using R

December 17, 2011
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Handwriting recognition using R

This title is a bit exaggerating since handwriting recognition is an advanced topic in machine learning involving complex techniques and algorithms. In this blog I’ll show you a simple demo illustrating how to recognize a single number (0 ~ 9) using R. The overall process is that, you draw a number in a graphics device in R using your mouse, and then the...

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Windows binary of RMySQL

October 21, 2011
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This binary package supports R 2.13.x (32-bit/64-bit) and MySQL 5.5.16 (32-bit/64-bit). RMySQL 0.8-0 for MySQL 5.5.16

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