& -> AND -> results only TRUE if both inputs are TRUE. Hence: FALSE AND unknown = FALSE, TRUE AND unknown = unknown | -> OR -> results in TRUE as soon as one of the inputs is TRUE. Hence FASE or unknown = unknown, TRUE or unknown = TRUE TRUE == NA and FALSE == NA compares TRUE/FALSE against unknown hence the output is unknown.
ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance Kliniekstraat 25 1070 Anderlecht Belgium To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey 2017-05-19 11:48 GMT+02:00 Ramnik Bansal <ramnik.ban...@gmail.com>: > Hi, > > I need to understand the inconsistent behaviour of & and I operators when > used with NA. > > The code below explains this inconsistency > > > TRUE & NA > [1] NA > > > FALSE & NA > [1] FALSE > > > TRUE & NA > [1] NA > > > FALSE | NA > [1] NA > > > TRUE | NA > [1] TRUE > > > TRUE == NA > [1] NA > > > FALSE == NA > [1] NA > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.