You cannot do a linear regression with one column of data - there must be at least one response column and one predictor. By default, lm throws in a constant term which gives you a second predictor. If your predictor is categorical, you get a new column for all but the first unique value in it.
lm() deals only with double precision data, at 8 bytes/number. Thus 250k numbers occupies 2 million bytes. Your three columns (in the non-categorical-predictor case) take up 6 million bytes, lm()'s output contains several columns the size of the response variable: residuals, effects, and fitted.values. It also contains the QR decomposition of the design matrix (the size of all the predictor columns together). There are also some temporary variables generated in the course of the computation. So your observed 40 MB memory usage seems reasonable. Use the object.size() function to see how big objects are and str() to look at their structure. My laptop with a 2.5 GHz Intel i7 processor takes a quarter second to fit a simple linear model with one numeric predictor and a constant term. 6 seconds sounds slow. Is that cpu or elapsed time (use system.time() to see)? Bill Dunlap TIBCO Software wdunlap tibco.com On Mon, Nov 16, 2015 at 12:25 PM, Sasikumar Kandhasamy <ckms...@gmail.com> wrote: > Hi All, > > I have couple of clarifications on R run-time performance. I have R-3.2.2 > package compiled for MIPS64 and am running it on my linux machine with > mips64 processor (core speed 1.5GHz) and observing the following behaviors, > > 1. Applying "linear regression model" (lm) on 1MB of data (contains 1 > column of 250K records) takes ~6 seconds to complete. Anyidea, is it an > expected behavior or not? If not, can you please the suggestions or options > to improve if we have any? > > 2. Also, the R process runtime virtual memory is increased by 40MB after > applying the linear model on 1MB data. Is it also expected behavior? If it > is expected, can you please share the insight of memory usage? > > Thanks in advance. > > Regards > Sasi > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
