Fast conversion of array to string in ruby

Question

I have an array of ~10,000 strings and integers that I want to serialize into a Rails web page. The eventual goal is to get the array into a JavaScript array, but I'm happy to just have it as a text blob that I then parse client side.

I can't cache the string, the values change every request.

This takes ~25ms on my VPS:

arr = ["ABCD", 1] * 10000 # always in string, number, string, number order
start = Time.now
arr.to_s
duration = (Time.now - start)*1000
puts "took #{duration}ms"

Can we do better?

edit

@sawa's answer is correct, to_json is fast and a good way to do this. I was getting thrown off because to_json in a Rails environment is overridden. Use JSON.generate(arr) instead.

sawa · Accepted Answer · 2012-11-29 18:46:13Z

6

JSON is faster as the array gets longer. As I tested with ["ABCD", 1] * n, when approx n < 50, to_s is faster, but when n > 50, to_json is faster.

arr = ["ABCD", 1] * 10000 # always in string, number, string, number order

start = Time.now
arr.to_s
duration = (Time.now - start)*1000
puts "took #{duration}ms"

require "json"
start = Time.now
arr.to_json
duration = (Time.now - start)*1000
puts "took #{duration}ms"

# =>
# took 7.546628ms # to_s
# took 4.684186ms # to_json

edited Nov 29, 2012 at 18:46

answered Nov 29, 2012 at 18:32

sawa

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1 Comment

spike Over a year ago

aha! i was too tied up trying things in my rails environment. I believe rails overrides to_json to do some sanitation, switched to JSON.generate(arr) and I see timing similar to what we get in the contrived example. Thanks!

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