Ruby gsub multiple characters in string

Question

Using Ruby 1.9.3, Rails 3.2, I have the following:

"every good boy does fine".gsub("every", "all").gsub("boy", "girl").gsub("fine", "well")
# => "all good girl does well"

Is there a better way to write this? Thanks.

Arup Rakshit · Accepted Answer · 2013-12-18T13:21:45.927

22

String#gsub and Hash#fetch will be the good choice for this.

a = "every good boy does fine"
h = {"every" => "all","boy" => "girl", "fine" =>"well" }
a.gsub(/\w+/) { |m| h.fetch(m,m)}
# => "all good girl does well"

or,

a = "every good boy does fine"
h = {"every" => "all","boy" => "girl", "fine" =>"well" }
Regexp.new("^#{h.keys.join('|')}$") # => /^every|boy|fine$/
a.gsub(Regexp.new("^#{h.keys.join('|')}$"),h)
# => "all good girl does well"

edited Dec 18 '13 at 13:21

answered Dec 18 '13 at 06:07

Arup Rakshit

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Clever use of `Regexp.union` however `'no finer boy'.gsub(Regexp.union(*h.keys),h)` -> `"no wellr girl"` – Matt Dec 18 '13 at 06:17
I find my original approach, though not the best, is more readable. Nevertheless, thanks for teaching. :) – Victor Dec 20 '13 at 04:13

score 4 · Answer 2 · answered Dec 18 '13 at 06:03

4

replacements = [ ["every", "all"], ["boy", "girl"],["fine", "well"]
replacements.each {|replacement| str.gsub!(replacement[0], replacement[1])}

I don't know if its better, but much cleaner.

answered Dec 18 '13 at 06:03

griffon vulture

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score 1 · Answer 3 · answered Dec 18 '13 at 06:09

1

subs = { "every" => "all", "boy" => "girl", "fine" => "well" }
"every good boy does fine".gsub(/\w+/) { |m| subs[m] || m }
# => 'all good girl does well'

answered Dec 18 '13 at 06:09

Matt

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`subs[m] || m` far better than `h.has_key?(m) ? h[m] : m` .. I forgot that, but you reminds me.. :) – Arup Rakshit Dec 18 '13 at 06:14
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`subs.default_proc = ->(h, k) { k }` is another option, then you could just say `{ |m| subs[m] }` and hide the conditional behind the `default_proc`. – mu is too short Dec 18 '13 at 06:30
@muistooshort More better is `a.gsub(/\w+/) { |m| h.fetch(m,m)}` :) Look at my edit. – Arup Rakshit Dec 18 '13 at 06:38

score 1 · Answer 4 · edited Mar 21 '22 at 06:57

1

just do this:

"every good boy does fine".gsub(/\w+/, 'every' => 'all', 'boy' => 'girl', 'fine' => 'well')

a lot easier to read :) some of the answers here to this simple question really make me wonder...lol

here's the reference: http://ruby-doc.org/core-2.1.4/String.html

gg

edited Mar 21 '22 at 06:57

ah bon

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answered Apr 21 '16 at 21:35

Beckster

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score 0 · Answer 5 · answered Dec 18 '13 at 06:08

If the intent is to avoid method chaining:

[9] pry(main)> "every good boy does fine".gsub("every", "all").gsub("boy", "girl").gsub("fine", "well")
=> "all good girl does well"
[10] pry(main)> "every good boy does fine".gsub(/(every)|(boy)|(fine)/) do |word|
[10] pry(main)*   case word
[10] pry(main)*   when "every"
[10] pry(main)*     "all"
[10] pry(main)*   when "boy"
[10] pry(main)*     "girl"
[10] pry(main)*   when "fine"
[10] pry(main)*     "well"
[10] pry(main)*   end
[10] pry(main)* end
=> "all good girl does well"

Alternatively:

[11] pry(main)> REPLACEMENT = { "every" => "all", "boy" => "girl", "fine" => "well"}
=> {"every"=>"all", "boy"=>"girl", "fine"=>"well"}
[12] pry(main)> "every good boy does fine".gsub(/(every)|(boy)|(fine)/) { |word| REPLACEMENT[word] }
=> "all good girl does well"

Ruby gsub multiple characters in string

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