http://qs1969.pair.com?node_id=11139306


in reply to Re^4: How Perl can push array into array and then how retrieve
in thread How Perl can push array into array and then how retrieve

G'day cavac,

"Your solution is probably a lot faster, ..."

I've always found for to be faster than map so I benchmarked. I ran the following with: 0 .. 5 (from the two nodes on which you commented); 0 .. 40 (the OP's original range); and, 0 .. 5000 (just to see if a large range made any significant different).

#!/usr/bin/env perl use strict; use warnings; use Benchmark 'cmpthese'; cmpthese 0 => { with_for => \&with_for, with_map => \&with_map, }; sub with_for { my @f; push @f, [$_+2, $_+1] for 0 .. 5; } sub with_map { my @f = map [$_+2, $_+1], 0 .. 5; }

I ran each three times; there was little difference in the results; I've just posted the middle results below.

# 0 .. 5 Rate with_map with_for with_map 602818/s -- -23% with_for 780657/s 30% -- # 0 .. 40 Rate with_map with_for with_map 92655/s -- -23% with_for 120756/s 30% -- # 0 .. 5000 Rate with_map with_for with_map 745/s -- -23% with_for 968/s 30% --

The smallest difference was -21% vs. 27%; the largest was -25% vs. 33%. As the range was increased, all values tended towards -23% vs. 30% (the middle values for all runs).

In this instance, for is faster than map (i.e. what I've always found in the past).

— Ken

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Re^6: How Perl can push array into array and then how retrieve [Benchmark]
by cavac (Priest) on Dec 03, 2021 at 12:22 UTC

    Thanks for taking the time to benchmark this.

    perl -e 'use Crypt::Digest::SHA256 qw[sha256_hex]; print substr(sha256_hex("the Answer To Life, The Universe And Everything"), 6, 2), "\n";'