Ruby function to merge two string into one

Question

Given two string like the ones below, I would like to merge them to generate the following. The results makes little sense, however, both strings have 'a sentence' in common, which is what counts as the connector between the two strings:

"This is a sentence is a great thing"

s1 = "This is a sentence" 

s2 = "a sentence is a great thing"

Is there a function for this in ruby?

score 2 · Accepted Answer · answered Jun 10 '12 at 09:09

Here's a solution that works.

def str_with_overlap(s1, s2)
  result = nil
  (0...(s2.length)).each do |idx|
    break result = s1 + s2[(idx + 1)..-1] if s1.end_with?(s2[0..idx])
  end
  result
end

str_with_overlap("This is a sentence", "a sentence is a great thing")
# => This is a sentence is a great thing

score 1 · Answer 2 · edited May 23 '17 at 12:03

1

As far as I know, there is no built-in function for this in Ruby.

You probably have to write an own function for this. The straightforward one runs in quadratic time in the input length. However, it is possible to do it in linear time in the input size by using this algorithm.

edited May 23 '17 at 12:03

Community

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answered Jun 10 '12 at 08:35

Allan D.

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Yuri Barbashov · Answer 3 · 2012-06-10T22:32:33.407

1

there is no built-in method in Ruby, but u can try this one

class String
  def merge str
    result = self + str
    for i in 1..[length,str.length].min
      result = self[0,length-i] + str if self[-i,i] == str[0,i]
    end
    result
  end
end

"This is a sentence".merge "a sentence is a great thing"

edited Jun 10 '12 at 22:32

answered Jun 10 '12 at 09:19

Yuri Barbashov

5,407
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for loop is the best in this case))... i don't know why do u h8 it)) – Yuri Barbashov Jun 10 '12 at 11:48
For example 1.upto is better in this case as it does not pollute main scope. (1..[length,str.length].min).each is probably best because it is most commonly seen. – pguardiario Jun 10 '12 at 22:06
main scope in this case is a function scope, so not a problem at all, but i have to admit that each is 10% faster on my system)) – Yuri Barbashov Jun 10 '12 at 22:27
The 10% is unimportant, the reason to avoid for loop is scope issues. – pguardiario Jun 10 '12 at 22:48

tokland · Answer 4 · 2012-06-10T12:51:51.260

0

Functional approach (works at word-level):

ws1, ws2 = [s1, s2].map(&:split)
idx = 0.upto(ws1.size-1).detect { |i| ws1[i..-1] == ws2[0, ws1.size-i] } || 0
(ws1[0, ws1.size-idx] + ws2).join(" ")
=> "This is a sentence is a great thing"

edited Jun 10 '12 at 12:51

answered Jun 10 '12 at 12:39

tokland

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Ruby function to merge two string into one

4 Answers4