Dear R Community,
One thing that always bugged me about R is the abundance of multi-level nested
statements, like:
cumsum(ifelse(c(1,diff(v)),1,0))
because:
a) you have to read them inside out as opposed to left-to-right
b) in the console you always have to go back and type the parenthesis if you
want to nest your statement
I kind of like the UNIX pipe operator as a very good abstraction of a data flow
and would fancy to have something like this in R:
v %|% diff %|% c(1, value) %|% ifelse(value, 1, 0) %|% cumsum
so I went ahead and wrote it:
"%|%" <- function(x,y)
{
# Operator similar to the UNIX pipe operator. Allows to set up a chain of
functions
# where the result of one function will be the input of the next.
#
# x: any R statement. will be passed to y as a parameter
# y: either a) the name of a single-parameter function or b) a function call,
where "value"
# will be replaced with the x parameter
#
# Example use 1: > c(1,2,3) %|% sum
# results in [1] 6
# Example use 2: > c(1,2,3) %|% rep(value, 10)
# results in [1] 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
thecall<-match.call() #get call
#for functions with one parameter call it with x. Example: "c(1,2,3)
%|% sum" -> 6
if(is.name(thecall$y) || is.function(thecall$y)) return (y(x))
#instead of value use x
value <- eval(thecall$x)
return(eval(thecall$y)) #evaluate
}
would be happy to receive some feedback on
1. Would you find this useful?
2. Is there any bugs/features that you'd like to mention?
3. Should I go ahead and make an R package on that?
Cheers,
Robert
[[alternative HTML version deleted]]
______________________________________________
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.
