It would be more interesting to ask why does this does not work. mylist <- list( value=5, plusplus = mylist$value + 1 )
I think this is because plusplus cannot be evaluated because mylist does not exist and mylist cannot be created until plusplus is evaluated. There are people on this list who can explain in more technical terms. But I think reading this page might help http://cran.r-project.org/doc/manuals/R-lang.html#index-evaluation_002c-symbol-166 Here is one option : mylist <- eval( expression( list( value=x, plusplus=x+1) ), list(x=5) ) mylist $value [1] 5 $plusplus [1] 6 Or a bit easier to read is : myfun <- function(x) list( value=x, plusplus=x+1 ) mylist <- myfun(5) Regards, Adai On Sat, 2005-11-12 at 01:03 -0600, Paul Roebuck wrote: > Can the value of a list element be referenced from a > sibling list element during list creation without the use > of a temporary variable? > > The following doesn't work but it's the general idea. > > > list(value = 2, plusplus = $value+1) > > such that the following would be the output from str() > > List of 2 > $ value : num 2 > $ plusplus: num 3 > > ---------------------------------------------------------- > SIGSIG -- signature too long (core dumped) > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
