I'd say what you did in the past was definitely a hack that made too strong assumptions on the internal implementation of lapply() etc. It basically relied on *apply() to loop over the elements using an index variable. There any many ways to do this and it seems like in R 3.2.0 there was change. Actually, it does also not work as you expect in R 3.1.3 (but you don't get the error). This is what you basically did:
## R 3.0.3: > essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) > idxs <- lapply(essai, function(x) substitute(x)[[3]]) > idxs $T2345 [1] 1 $T5664 [1] 2 ## R 3.1.3: > essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) > idxs <- lapply(essai, function(x) substitute(x)[[3]]) > idxs $T2345 [1] 2 $T5664 [1] 2 NOTE how you don't get indices you expect, and therefor not the names either. ## R 3.2.0: > essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) > idxs <- lapply(essai, function(x) substitute(x)[[3]]) > idxs $T2345 i $T5664 i The latter will obviously not work as indices. My rule of thumb: Anytime you find yourself using substitute() and get()/assign(), there's probably a better way to do it. Example: > essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) > lapply(seq_along(essai), function(idx) plot(essai[[idx]], > main=names(essai)[idx])) or > essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) > mapply(essai, names(essai), FUN=function(x, name) plot(x, main=name)) If names are unique, this also works: > essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) > lapply(names(essai), function(name) plot(essai[[name]], main=name)) /Henrik On Sun, Apr 26, 2015 at 1:28 PM, Marc Girondot <marc_...@yahoo.fr> wrote: > Dear list-members, > I find a annoying difference between R 3.1.3 and R 3.2. > > To get the element name of a list within lapply() or mclapply() call, I used > the trick below: > For example: > > essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) > lapply(essai, function(x) plot(x, main= names(essai)[substitute(x)[[3]]])) > > It works fins in R 3.1.3 however in R 3.2 it produces an error: >> essai <- list(T2345=c(5, 6, 7), T5664=c(9, 12, 17, 16)) >> lapply(essai, function(x) plot(x, main= names(essai)[substitute(x)[[3]]])) > > Error in names(essai)[substitute(x)[[3]]] : > type 'symbol' d'indice incorrect > > I don't see if this difference is noted is the list of changes: > http://cran.r-project.org/doc/manuals/r-devel/NEWS.html > > If it is not a bug but a feature, what is the new way to get the list > element name within a lapply or mclappy function. > > Thanks a lot > > Marc Girondot > > ______________________________________________ > 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. ______________________________________________ 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.
