Charles Dupont wrote: > I was messing around with R and I found an example R behaving oddly: > > a <- alist(NULL, "bob", c(3,6,2,3)) > a > a == 'NULL' > a == "NULL" > a == 'cat' >
Always use is.null() to test on NULL, as in: sapply(a, is.null) Uwe Ligges > If I create a list with a NULL value > >a <- alist(NULL, "bob", c(3,6,2,3)) > >a > [[1]] > NULL > > [[2]] > [1] "bob" > > [[3]] > c(3, 6, 2, 3) > > and run some tests on 'a', the '== "NULL' test returns TRUE for the NULL > entry in the list 'a'. > >a == 'NULL' > [1] TRUE FALSE FALSE > >a == "NULL" > [1] TRUE FALSE FALSE > >a == 'cat' > [1] FALSE FALSE FALSE > > This is consistent for every example of NULL's in a list that I can > think of. > > Is this a bug or undocumented correct behavior? > > Here is my version output > > platform i486-pc-linux-gnu > arch i486 > os linux-gnu > system i486, linux-gnu > status > major 2 > minor 2.0 > year 2005 > month 10 > day 06 > svn rev 35749 > language R > > > Thanks > > Charles ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
