How about ceiling(x), which return the smallest integer not less than x? On Sun, May 17, 2009 at 2:49 AM, Thomas Mang <thomas.m...@fiwi.at> wrote: > Hello, > > Suppose I have x, which is a variable of class numeric. The calculations > performed to yield x imply that mathematically it should be an integer , but > due to round-off errors, it might not be (and so in either direction). The > error is however small, so round(x) will yield the appropriate integer > value. Moreover, this integer values is guaranteed to be representable by an > 'integer' class, that is -2^31 < x < 2^31, and logically it is an integer > anyway. So I want to convert x from class 'numeric' to 'integer'. What is > the most elegant, but always correct way, to achieve this conversion ? > > What comes to mind is of course something along: > > x = as.integer(round(x)) > > I am, however, not sure if this always works, because I do not know if the > round-function is guaranteed to return a numeric value which, in finite > binary representation, is always >= the underlying mathematical integer. If > that is however guaranteed, that would of course be a simple + elegant one. > > An alternative I came up with is: > > x = as.integer(round(x) + ifelse(x >= 0, 0.5, -0.5)) > Where I explicitly add a bit to ensure the finite binary representation must > be >= the underlying integer, and then truncate the decimal digits. > IMO, this one is always guaranteed to work, at least within the numerical > range of what integers are limited to anyway. > > > What's your opinion on the issue ? > Any other solution ? > > Thanks a lot in advance and cheers, > Thomas > > ______________________________________________ > 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.
