I have been reading this thread and I am having a hard interpreting what these mean. I know that the result is that all of the values that are zero in a are replaced by NA. Let me try and write it out
is.na(a[a==0] ) <- TRUE you pull out of a all of the times that are equal to zero then is.na tests and returns false then all of the false values are set to true? is.na(a) <- a==0 make values in a NA when a is 0? is this right? what the logic if not? thanks Stephen Sefick On Tue, Aug 12, 2008 at 6:32 PM, Charles C. Berry <[EMAIL PROTECTED]> wrote: > On Tue, 12 Aug 2008, Mike Prager wrote: > >> rcoder <[EMAIL PROTECTED]> wrote: >> >>> I have a matrix that has a combination of zeros and NAs. When I perform >>> certain calculations on the matrix, the zeros generate "Inf" values. Is >>> there a way to either convert the zeros in the matrix to NAs, or only >>> perform the calculations if not zero (i.e. like using something similar >>> to >>> an !all(is.na() construct)? >> >> Is this what you are looking for? >> >>> # make some data >>> a = matrix(c(rep(0,6), rep(2,6)), nrow = 4) >>> a >> >> [,1] [,2] [,3] >> [1,] 0 0 2 >> [2,] 0 0 2 >> [3,] 0 2 2 >> [4,] 0 2 2 >>> >>> # change zero to NA >>> is.na(a[a==0] ) <- TRUE > > Or > is.na(a) <- a==0 > > Chuck > >>> a >> >> [,1] [,2] [,3] >> [1,] NA NA 2 >> [2,] NA NA 2 >> [3,] NA 2 2 >> [4,] NA 2 2 >> >> -- >> Mike Prager, NOAA, Beaufort, NC >> * Opinions expressed are personal and not represented otherwise. >> * Any use of tradenames does not constitute a NOAA endorsement. >> >> ______________________________________________ >> 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. >> > > Charles C. Berry (858) 534-2098 > Dept of Family/Preventive > Medicine > E mailto:[EMAIL PROTECTED] UC San Diego > http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 > > ______________________________________________ > 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. > -- Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis ______________________________________________ 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.
