Since 0 can be represented exactly as a floating point number, there is no problem with something like x[x==0]. What you can not rely on is something like 0.1+0.2 == 0.3 to be TRUE.
--- On Thu, 14/8/08, Roland Rau <[EMAIL PROTECTED]> wrote: > From: Roland Rau <[EMAIL PROTECTED]> > Subject: Re: [R] ignoring zeros or converting to NA > To: "rcoder" <[EMAIL PROTECTED]> > Cc: r-help@r-project.org > Received: Thursday, 14 August, 2008, 1:23 AM > Hi, > > since many suggestions are following the form of > x[x==0] (or similar) > I would like to ask if this is really recommended? > What I have learned (the hard way) is that one should not > test for > equality of floating point numbers (which is the default > for R's numeric > values, right?) since the binary representation of these > (decimal) > floating point numbers is not necessarily exact (with the > classic > example of decimal 0.1). > Is it okay in this case for the value zero where all binary > elements are > zero? Or does R somehow recognize that it is an integer? > > Just some questions out of curiosity. > > Thank you, > Roland > > > rcoder wrote: > > Hi everyone, > > > > 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)? > > > > Thanks, > > > > rcoder > > ______________________________________________ > 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. ______________________________________________ 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.
