How to run a function multiple times and write the results to a list?
Combination of above answer, comment, and my own answer. Naturally, I like mine better. Also, I think there is a mistake in the above answer for base
R.
n <- 10
# give 1 to gen_mat n-times
lapply(rep(1, n), gen_mat)
# replicate n-times
replicate(n, gen_mat(1), simplify=FALSE)
# lapply returns error if FUN is not function or
# the function is not taking an argument. Hence a dummy function.
lapply(seq_len(n), function(x) gen_mat(1))
microbenchmarking the three methods
I used a larger value for n
, but the results are similar in my desktop with smaller n
as well. For this, replicate
takes longer than the other two methods.
set.seed(1)
gen_mat <- function(x) matrix(c(1, 1, 1, x + rnorm(1)), nrow = 2)
n <- 1000
library(microbenchmark)
library(ggplot2)
mb <- microbenchmark(
lap1 = {lapply(rep(1, n), gen_mat)},
repl = {replicate(n, gen_mat(1), simplify=FALSE)},
lap2 = {lapply(seq_len(n), function(x) gen_mat(1))},
times = 10000L
)
mb
# Unit: milliseconds
# expr min lq mean median uq max neval cld
# lap1 2.839435 3.494157 4.806954 3.854269 5.611413 103.0111 10000 a
# repl 3.091829 3.777199 5.140789 4.165856 6.013591 101.4318 10000 b
# lap2 3.131491 3.761274 5.089170 4.140316 5.939075 101.1983 10000 b
autoplot(mb)
base
R
n <- 10
lapply(seq_len(n), gen_mat(1))
purrr
package
library(purrr)
map(seq_len(n), ~gen_mat(1))