[R] very slow "memoise"
Martin Møller Skarbiniks Pedersen
tr@xpl@yer @ending from gm@il@com
Thu Nov 15 13:44:05 CET 2018
Hi,
I want to compute a lot of values and I have tried to use
memoise::memoise to speed-up the computation.
However it is much slower using the memoised version.
I guess I have misunderstood how to use the package memoise or the
purpose of the package.
The code takes more than 2 minutes to finish but if I remove the line:
"nextstep <- memoise(nextstep)" the code runs in less than 1 second. I
was expecting a
total different result.
Here are the code:
library(memoise)
nextstep <- function(num) {
if (num %% 2 == 0) {
return(num/2)
}
num*3+1
}
nextstep <- memoise(nextstep)
for (idx in 1:1e4) {
steps <- 0
current <- idx
while (current != 1) {
steps <- steps + 1
current <- nextstep(current)
}
cat(idx,steps,"\n")
}
Regards
Martin
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