Hi,
I would like to make a suggestion for a small syntactic modification of
FUN argument in the family of functions [lsv]apply(). The idea is to
allow one-liner expressions without typing "function(item) {...}" to
surround them. The argument to the anonymous function is simply referred
as ".". Let take an example. With this new feature, the following call
sapply(split(mtcars, mtcars$cyl), function(d) summary(lm(mpg ~ wt,
d))$r.squared)
# 4 6 8
#0.5086326 0.4645102 0.4229655
could be rewritten as
sapply(split(mtcars, mtcars$cyl), summary(lm(mpg ~ wt, .))$r.squared)
"Not a big saving in typing" you can say but multiplied by the number of
[lsv]apply usage and a neater look, I think, the idea merits to be
considered.
To illustrate a possible implementation, I propose a wrapper example for
sapply():
wsapply=function(l, fun, ...) {
s=substitute(fun)
if (is.name(s) || is.call(s) && s[[1]]==as.name("function")) {
sapply(l, fun, ...) # legacy call
} else {
sapply(l, function(d) eval(s, list(.=d)), ...)
}
}
Now, we can do:
wsapply(split(mtcars, mtcars$cyl), summary(lm(mpg ~ wt, .))$r.squared)
or, traditional way:
wsapply(split(mtcars, mtcars$cyl), function(d) summary(lm(mpg ~ wt,
d))$r.squared)
the both work.
How do you feel about that?
Best,
Serguei.
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