Ruby - substituting characters in a string with sequential elements of an array

Question

I have a string:

a = 'bla \n bla \n bla \n'

And an array:

b = ['1', '2', '3']

I want to search through the string, and replace every nth instance of \n with the (n-1)th element from the array, resulting in:

a = 'bla 1 bla 2 bla 3'

What is the simplest way for me to do this?

Are you trying every permutation of every possible question with the same structure but different objects? — Eric Duminil
– Eric Duminil, Commented Dec 6, 2016 at 14:53
While the topic was similar the given responses are completely different. Some people replying took the time to give answers, one of which has helped me greatly. — Mark
– Mark, Commented Dec 6, 2016 at 14:57

Jordan Running · Accepted Answer · 2016-12-06 13:46:04Z

5

String#gsub with a block makes short work of this:

a.gsub('\n') { b.shift }

Note that Array#shift modifies the original array. Make a copy of it first (b.dup) if that's a problem.

answered Dec 6, 2016 at 13:46

Jordan Running

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1 Comment

I thinking about it, nice!)

Oleksandr Holubenko · Accepted Answer · 2016-12-06 13:44:01Z

1

You can use method sub

a = 'bla \n bla \n bla \n'
b = ['1', '2', '3']
b.each { |i| a.sub!('\n', i) }
#> a
#=> "bla 1 bla 2 bla 3"

answered Dec 6, 2016 at 13:44

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engineersmnky · Accepted Answer · 2016-12-06 14:49:18Z

1

Just one more way using String#split and Array#zip

a.split('\n').zip(b).join
#=> "bla 1 bla 2 bla 3"

answered Dec 6, 2016 at 14:49

engineersmnky

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It looks like the best answer to me. Short, to the point and non-destructive. Sorry, I'm all out of votes.