Re: [R] assigning vector or matrix sparsely (for use with mclapply)

It is (at least for me) really unclear what the problem is, or how it's related to mclapply. You say this works fine, except that what I want to get NA's in the return positions that were not recalculated. then, I can write newdata$y - ifelse ( is.na(olddata$y), mc.byselectrows( olddata,

Re: [R] assigning vector or matrix sparsely (for use with mclapply)

I wasn't thinking straight. old.data= 11:20 recalc.please= (old.data%%2==0) old.data[recalc.please] [1] 12 14 16 18 20 new.data[recalc.please]= old.data[recalc.please]^2 Error in new.data[recalc.please] = old.data[recalc.please]^2 : object 'new.data' not found # this is where I had given

[R] assigning vector or matrix sparsely (for use with mclapply)

Dear R wizards--- I have a wrapper on mclapply() that makes it a little easier for me to do multiprocessing. (Posting this may make life easier for other googlers.) I pass a data frame, a vector that tells me what rows should be recomputed, and the function; and I get back a vector or matrix of