Split a string into parts in efficient way

Question

My code is here

str = "Early in his first term in office, Obama signed into law economic stimulus legislation in response"
arr= str.split(" ")
set_element= arr.each_cons(2).to_a
sub_str = set_element.map {|i| i.join(' ')}

If i have a big string like very big string then this process take 6.50 sec because i want to this type of result

sub_str= ["Early in", "in his", "his first", "first term", "term in", "in office,", "office, Obama", "Obama signed", "signed into", "into law", "law economic", "economic stimulus", "stimulus legislation", "legislation in", "in response"]

Is it possible any another way with efficient way

dbenhur · Accepted Answer · 2013-03-22 06:32:02Z

7

Use scan instead of split and you can get your word pairs directly.

s.scan(/\S+(?:\s+\S+)?/)

EDIT: Just to assure myself that this was relatively efficient, I made a little micro-benchmark. Here's results for the answers seen to date:

ruby 1.9.3p125 (2012-02-16 revision 34643) [x86_64-linux]
10 times on string of size 2284879
                 user     system      total        real
original     4.180000   0.070000   4.250000 (  4.272856)
sergio       2.090000   0.000000   2.090000 (  2.102469)
dbenhur      1.050000   0.000000   1.050000 (  1.042167)

edited Mar 22, 2013 at 6:32

answered Mar 22, 2013 at 6:13

dbenhur

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1 Comment

Ravendra Kumar Over a year ago

awesome i have no word for this

Sergio Tulentsev · Accepted Answer · 2013-03-22 05:45:05Z

1

set_element = arr.each_cons(2).to_a

The line above creates a ton of temporary objects that you don't need. Try this, should be faster:

str = "Early in his first term in office, Obama signed into law economic stimulus legislation in response"
arr = str.split(" ")
sub_str = arr.each_with_object([]).with_index do |(el, memo), idx|
  if idx % 2 == 0
    memo << el
  else
    memo.last << ' ' << el
  end

end

sub_str # => ["Early in", "his first", "term in", "office, Obama", "signed into", "law economic", "stimulus legislation", "in response"]

answered Mar 22, 2013 at 5:45

Sergio Tulentsev

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Comments

user946611 · Accepted Answer · 2013-03-22 10:35:13Z

0

You can try this. one step less :)

arr= str.scan(/\S+/)
s = []
arr.each_with_index { |x, i| s << (x + " " + arr[i + 1]) if arr[i+1] }

answered Mar 22, 2013 at 10:35

user946611

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