(This article was first published on

**Xi'an's Og » R**, and kindly contributed to R-bloggers)**W**hen I ran

> test=NULL > for (i in 1:10){ + if (i%%2!=0){ + test=c(test,i) + i=i+2}} > test [1] 1 3 5 7 9

I was expecting the same output as

> test=NULL > i=1 > while (i test [1] 1 5 9

So this means that the dummy index in R “for” loops cannot be tweaked that easily. I seem to remember doing this kind of (dirty) tricks with earlier versions… Now, Alessandra and Robin think this is a good thing that the ** for** loop is robust against this kind of non-sense, so I may be a minority in complaining about this lack of control [for me, if not for

**].**

*for*Filed under: R, University life Tagged: dummy variable, for loop, loops, R

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