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Python vs Ruby?
I was trying to run a little "benchmark" today, so to speak, to give me a better idea as to which language I should choose for a project I'm planning on starting soon.

I'm going to have to iterate over large arrays for this project, so I decided to give it a go at seeing the difference in performance when it came to inserting numerous objects into an array, and then transferring those objects one-by-one to a string.  Here's the code I used:

Python


testlist = []
transfer = ""

for i in range(1,1000001):
  testlist.append(i)

for i in testlist:
  transfer += str(i)


Ruby


testlist = []
transfer = ""

1.upto(1000000) do |i|
  testlist.push(i)
end

testlist.each do |n|
  transfer += n.to_s
end

Now, the two seem very similar in program flow (at least, to me).  So I ran the Python program.  This is what I got:

real    0m1.679s
user    0m1.484s
sys     0m0.184s

Ok, so it played with 1 million objects (well... technically more than double that) in under 2 seconds.  Sounds good so far!  Now, when I ran the Ruby program, this is what I got:

*snoring*

Well, I didn't really get that, but I had to Ctrl+C the thing after over 67 minutes!  What went wrong?  Well, I went ahead and broke symmetry and changed the last block of code to look like this:

testlist.each do |n|
  transfer << n.to_s
end

And I finally got some sane results:

real    0m4.103s
user    0m3.456s
sys     0m0.644s

Now, while this shows me that Python was able to perform this operation significantly faster than Ruby (and will certainly hold weight when it comes to choosing the language I will use), I'm still thoroughly confused as to why the previous method didn't work!  Maybe I just don't know enough about string concatenation (after posting this I'm going to go reread that section in "Programming Ruby: The Pragmatic Programmer's Guide").  Anyone have any ideas?  I'd like to hear them.  It's likely just something I totally overlooked, as usual ;)

Anyway, in case you were wondering, it really is recommended to use "<<" instead of "+" for string concatenation, because it is faster.
Last Updated on Sunday, 08 February 2009 04:57
 

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