Partial function application in R
Well, it looks like it's a perfectly correct approach to bind functions writing their wrappers by hand. But I don't want to write them by hand every time I need them. Being lambda expression, function() is most general, but there must be some kind of shorter way for such a common task as partial application.
David Winsemius wrote:
How is function() not the correct approach?
> plot_lines <- function(x, ...) plot(x, type="l", ...) > > plot_lines(1:10, xlim = c(1,5))
> plot_lines(1:10, 11:20, xlim = c(1,5))
Still seems to get the unnamed optional y argument to the plotting machinery. -- David Winsemius On Jan 15, 2009, at 4:25 PM, nosek wrote:
Hello,
in a desperate desire of using partial function application in R I
fried out
the following piece of code:
bind <- function( f, ... ) {
args <- list(...)
function(...) f( ..., unlist(args) )
}
Its purpose, if not clear, is to return a function with part of its
arguments bound to specific values, so that I can for example create
and use
functions like this:
q1 <- bind( quantile, 0.25 )
lapply( some_list, q1 )
It's been a lot of work and unfortunately is not perfect. My bind
applies
arguments only using positional rule. What I dream of is a function
bind2
that would apply keyword arguments, like:
plot_lines <- bind2( plot, type="l" )
which would return
function(...) plot( type="l", ... )
How to do this in R?
Regards,
nosek
--
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