On 07/05/2011 7:09 PM, William Revelle wrote:
Dear friends,How do I stop partial matching of list names? e.g., x<- list(AAAA="aaaaa", BBBBB="bbbbb") is.null(x$A) #returns FALSE even though there is no element A. if(is.null(x$A)) {result<- x$BBBB} else {result<- x$A} result #is aaaa even though there is no x$A element x<- list(CCCC="aaaaa", BBBBB="bbbbb") if(is.null(x$A)) {result<- x$BBBB} else {result<- x$A} result #this is great x<- list(ABC="aaaaa", BBBBB="bbbbb") if(is.null(x$A)) {result<- x$BBBB} else {result<- x$A} result #partial matches and returns aaaa x<- list(ABC="abc", BBBBB="bbbbb",AA="aaaa") if(is.null(x$A)) {result<- x$BBBB} else {result<- x$A} result #can not partial match, and thus returns bbbb x<- list(AAB="aab", BBBBB="bbbbb",AA="aaaa") if(is.null(x$A)) {result<- x$BBBB} else {result<- x$A} result #also can not partial match My need for this is that I have several functions that return lists and I am trying to extract AAAA if it exists, but something else if it does not.
Both "A" %in% names(x) will return false, and is.null(x[["A"]]) will return TRUE. Duncan Murdoch ______________________________________________ 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.
