R: simple and short if clauses for combind statements

Question

TRUE/FALSE if clauses are easily and quickly done in R. However, if the argument gets more complex, it also gets ugly very soon.

For instance: I might want to execute different operations for a row(foo) dependent on the value in one cell (foo[1]). Let the intervals be 0:39 and 40:59 and 60:100

Something like does not exit:

(if foo[1] "in" 40:60){...

In fact, I only see ways of at least two if clauses and two else statements and the action for the first interval somewhere at the bottom of the code. With more intervals(or any other condition) it is getting more complex.

Is there a best practice (for this purpose or others) with a simple construction and nice design to read?

Answer 1

Not totally following your question. Are you looking for a switch statement? Have a look at this example:

ccc <- c("b","QQ","a","A","bb")
for(ch in ccc)
     cat(ch,":",switch(EXPR = ch, a=1,     b=2:3), "\n")

Answer 2

Not totally sure, but I would suggest to use something like:

f <- approxfun(0:100,c(rep(1,40),rep(2,20),rep(3,41)),method="c")
fac <- f(foo)
tapply(foo,fac,FUN,...)

where you can use any function FUN.