From: rm_rails@...
Date: 2006-04-24T19:53:25+09:00
Subject: Re: array.concat(a) vs array.push(*a)


Hmm... perhaps answering my own question ....
array.push(*a) segfaults more than concat does....

> > a = [1,2,3,4,5]; puts Benchmark.measure{ (1..20).each{ a.concat(a)}}
   0.100000   0.040000   0.140000 (  0.143773)
=> nil
> > a = [1,2,3,4,5]; puts Benchmark.measure{ (1..20).each{ a.push(*a)}}
Segmentation fault



On Mon, 24 Apr 2006, rm_rails@cheapcomplexdevices.com wrote:

>
>
> It feels to me like array.concat seems slower than the equivalent (I think) 
> variation using array.push:
>
>>> a = [1,2,3,4,5]; b=[]; puts Benchmark.measure{ (1..100000).each{ 
>>> b.push(*a)}}
>  0.090000   0.000000   0.090000 (  0.090436)
>
>>> a = [1,2,3,4,5]; b=[]; puts Benchmark.measure{ (1..100000).each{ 
>>> b.concat(a)}}
>  0.290000   0.000000   0.290000 (  0.296501)
>
> (using ruby 1.8.4)
>
> This surprised me somewhat, because earlier
> (http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/7521)
> it was suggested that concat is a fast way of appending to arrays.
>
>
> Is there something I'm missing, or does it seem I should be
> using push(*a) in places where I had been using concat(a)?
>