Gabor,
Thank you for drawing this previous work to my attention. I've attached
below code that extends the list comprehension to include logical
'guard' expressions, as in
> leap.years <- .[ x ~ x <- 1900:2100 | (x %% 400 == 0 || x %% 100 != 0
&& x %% 4 == 0) ]
> leap.years
[1] 1904 1908 1
That seems quite nice.
Note that there has been some related code posted. See:
http://tolstoy.newcastle.edu.au/R/help/03b/6406.html
which discusses some R idioms for list comprehensions.
Also the gsubfn package has some functionality in this direction. We
preface any function with fn$ to allow
Below is code that introduces a list comprehension syntax into R,
allowing expressions like:
> .[ sin(x) ~ x <- (0:11)/11 ]
[1] 0. 0.09078392 0.18081808 0.26935891 0.35567516 0.43905397
[7] 0.51880673 0.59427479 0.66483486 0.72990422 0.78894546 0.84147098
> .[ .[x*y ~ x <- 0:3] ~ y <-
