On May 9, 2011, at 11:12 , Martyn Byng wrote: > I wonder if someone with more experience than me on using R to summarise > by group wants to post a reply to this
Not really (but how did those people manage to overlook by()?). However, another matter PLEASE DO NOT BE SO B***DY LAZY AND START A NEW TOPIC AS A REPLY TO SOMETHING COMPLETELY UNRELATED. Those of us with threading mail clients, will see your post as part of the thread "maximum likelihood convergence reproducing Anderson Blundell 1982 Econometrica R vs Stata" and, at least with Mac OSX's Mail, the header of the entire thread is now "Summarising by group". Peter D. > > http://www.analyticbridge.com/group/sasandstatisticalprogramming/forum/t > opics/why-still-use-sas-with-a-lot > > To save everyone having to follow the link, the text is copied below > > "SAS has some nice features, such as the SQL procedure or simple "group > by" features. Try to compute correlations "by group" in R: say you have > 2,000 groups, 2 variables e.g. salary and education level, and 2 million > observations - you want to compute correlation between salary and > education within each group. > > It is not obvious, your best bet is to use some R package (see sample > code on Analyticbridge to do it), and the solution is painful, you can > not return both correlation and stdev "by group", as the function can > return only one argument, not a vector. So if you want to return not > just two, but say 100 metrics, it becomes a nightmare." > > > > ________________________________________________________________________ > The Numerical Algorithms Group Ltd is a company registered in England > and Wales with company number 1249803. The registered office is: > Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom. > > This e-mail has been scanned for all viruses by Star. Th...{{dropped:4}} > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Peter Dalgaard Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
