Zhuo Yao, Ph.D.

Overview In this example, we look at how we can send multiple HTTP requests and process them concurrently. The basic idea is this. We specify…

View More Multiple Concurrent Downloads using RCurl

Overview The RCurl package provides high-level facilities in R to communicate with HTTP servers. Simply, it allows us to download URLs, submit forms in different…

View More R Deal with Web Data and Content

SQLDF provides a nice solution a1 <- data.frame(a = 1:5, b=letters[1:5]) a2 <- data.frame(a = 1:3, b=letters[1:3]) require(sqldf) a1NotIna2 <- sqldf(‘SELECT * FROM a1 EXCEPT…

View More Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2

12 months ago Marco Ghislanzoni [Total: 1    Average: 3/5] I noted that a previous post about Pivot Tables in R with melt and cast…

View More Pivot Tables in R with aggregate

about a year ago Marco Ghislanzoni [Total: 10    Average: 2.5/5] If you are making the transition from Excel to R and still can’t figure…

View More Pivot Tables in R with melt and cast

Pivot Tables in R with dplyr 6 months ago Marco Ghislanzoni [Total: 4    Average: 4/5] The prolific Hadley Wickham did it again! This time he…

View More Pivot Tables in R with dplyr

A common data-munging operation is to compute cross tabulations of measurements by categories. SQL Server and Excel have a nice feature called pivot tables for…

View More Pivot tables in R

To write it, it took three months; to conceive it – three minutes; to collect the data in it – all my life. F. Scott…

View More sqldf SQL on R data frames

Introduction For those who are learning R and who may be well-versed in SQL, thesqldf package provides a mechanism to manipulate R data frames using…

View More Manipulating Data Frames Using sqldf – A Brief Overview