Duncan suggested to use the argument explicitly and combine it with the missing function which is for this problem also my preferred solution:
image.2 <- function(x, col , breaks, ...){ # function is manipulating colors (adding a few) # since it changes colors it needs to update breaks if defined. if( !missing(breaks) ){ #manipulate breaks image(x, col, breaks ,...) }else{ image(x,col ,...) } } It is good to know that I also could have used do.call. I also learned yesterday that it is better to search for dot dot dot argument or for elipsis instead of ... best On 11 May 2016 at 15:45, Vito M. R. Muggeo <vito.mug...@unipa.it> wrote: > Hi Witold, > use do.call() > > list.args<-list(...) > > #modify 'list.args' (add/delete/modify) > > do.call(image, list.args) > > best, > vito > > > Il 11/05/2016 10.45, Witold E Wolski ha scritto: >> >> Hi, >> >> I am looking for a documentation describing how to manipulate the >> "..." . Searching R-intro.html gives to many not relevant hits for >> "..." >> >> What I want to do is something like this : >> >> >> image.2 <- function(x, col , ...){ >> # function is manipulating colors (adding a few) >> # since it changes colors it needs to update breaks if defined. >> >> breaks <- list(...)$breaks >> >> if( !is.null( list(...)$breaks ) ){ >> #manipulate breaks >> >> image(x, col, breaks = breaks ,...) >> >> }else{ >> image(x,col ,...) >> } >> } >> >> but in order to get it working I will need to remove breaks from ... >> since otherwise I am getting multiple defined argument for breaks. >> >> So how to manipulate the "..." argument? Or should I use a different >> pattern >> >> best >> >> >> > > -- > ============================================== > Vito M.R. Muggeo > Dip.to Sc Statist e Matem `Vianelli' > Università di Palermo > viale delle Scienze, edificio 13 > 90128 Palermo - ITALY > tel: 091 23895240 > fax: 091 485726 > http://dssm.unipa.it/vmuggeo > Associate Editor, Statistical Modelling > =============================================== -- Witold Eryk Wolski ______________________________________________ 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.