The Art of R Programming

Though R usually adheres to copy-on-change semantics, there are excep- tions. For example, R doesn’t exhibit the location-change ...

But things can get very subtle when it comes to R performance issues, so let’s try it out. > m <- 5000 > n <- 1000 & ...

argument to stop the monitoring. Finally, we’ll callsummaryRprof()to see the results. x <- runif(1000000) Rprof() invisible( ...

$sampling.time [1] 0.56 What aboutpowers3(), the promising approach that didn’t pan out? > Rprof() > invisible(powers3(x,8 ...

So,Rprof()often found that at inspection time,powers3()had called outer(), which in turn had calledFUN(), the latter being the c ...

14.5 Byte Code Compilation..................................................... Starting with version 2.13, R has included abyte ...

the counts or totals for that chunk and record them. After reading all the chunks, we add up all the counts or totals in order t ...

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15 INTERFACING R TO OTHER LANGUAGES R is a great language, but it can’t do every- thing well. Thus, it is sometimes desirable to ...

To work in UDP, you need C/C++, which requires an interface to R for those languages. R actually offers two C/C++ interfaces via ...

Here, we would say that we are traversing that long vector with a stride of 1,000—that is, accessing every thousandth element. 1 ...

15.1.4 Debugging R/C Code........................................... Chapter 13 discussed a number of tools and methods for debu ...

We told GDB to resume executing R (we needed to hit theENTERkey a second time in order to get the R prompt): (gdb) continue We ...

for (i in 1:(n-k)) { if (sum(x[i:(i+(k-1))]) >= k2) pred[i] <- 1 else pred[i] <- 0 } return(mean(abs(pred-x[(k+1):n]))) ...

That’s even more compact than our first version. But it’s a lot harder to read, and for reasons we will explore soon, it may not ...

The speedup is breathtaking. You can see that writing certain functions in C can be worth the effort. This is especially true fo ...

consider a call to the R linear model functionlm(). In our example, we will predictbfroma. a = [5,12,13] b = [10,28,30] lmout ...

First, we usedr.assign()to copy a variable from Python’s namespace to R’s. We then ranexpand.grid()(with a period in the name in ...

16 PARALLEL R Since many R users have very large compu- tational needs, various tools for some kind of parallel operation of R h ...

over all pairs of websites in our data set. This mean can be found using the following outline, for ann-by-nmatrix: 1 sum=0 2 fo ...