switch() statement usage

Well, timing to the rescue again. It seems switch is generally faster than if statements.
So that, and the fact that the code is shorter/neater with a switch statement leans in favor of switch:

# Simplified to only measure the overhead of switch vs if

test1 <- function(type) {
 switch(type,
        mean = 1,
        median = 2,
        trimmed = 3)
}

test2 <- function(type) {
 if (type == "mean") 1
 else if (type == "median") 2
 else if (type == "trimmed") 3
}

system.time( for(i in 1:1e6) test1('mean') ) # 0.89 secs
system.time( for(i in 1:1e6) test2('mean') ) # 1.13 secs
system.time( for(i in 1:1e6) test1('trimmed') ) # 0.89 secs
system.time( for(i in 1:1e6) test2('trimmed') ) # 2.28 secs

Update With Joshua’s comment in mind, I tried other ways to benchmark. The microbenchmark seems the best. …and it shows similar timings:

> library(microbenchmark)
> microbenchmark(test1('mean'), test2('mean'), times=1e6)
Unit: nanoseconds
           expr  min   lq median   uq      max
1 test1("mean")  709  771    864  951 16122411
2 test2("mean") 1007 1073   1147 1223  8012202

> microbenchmark(test1('trimmed'), test2('trimmed'), times=1e6)
Unit: nanoseconds
              expr  min   lq median   uq      max
1 test1("trimmed")  733  792    843  944 60440833
2 test2("trimmed") 2022 2133   2203 2309 60814430

Final Update Here’s showing how versatile switch is:

switch(type, case1=1, case2=, case3=2.5, 99)

This maps case2 and case3 to 2.5 and the (unnamed) default to 99. For more information, try ?switch