Flatten an array of strings in Ruby

Question

What's the best idiomatic (cleanest) way to convert an array of strings into a string, while keeping the enclosing quotes for each elements.
In other words, from this:

a = ["file 1.txt", "file 2.txt", "file 3.txt"]

I'd need to get this

"'file 1.txt' 'file 2.txt' 'file 3.txt'"

Single and double quotes could be interchanged here. The best ways I know of is by using map and inject/reduce.

eg: a.map{|dir| "'" + dir + "'"}.join(' ')
eg2: a.reduce("'"){|acc, dir| acc += dir+"' "}

Performance could be improved by avoiding temp string creation (+ operator). That's not my main question though. Is there a cleaner more concise way to achieve the same result?

No, only to keep the beginning and end quotes as shown above for the array. I realise that the quotes shown are not in the strings themselves and that's why they are stripped when doing only a join on the array. — Bernard
– Bernard, Commented Aug 19, 2010 at 23:04

captainpete · Accepted Answer · 2013-07-02 01:05:17Z

29

Shorter doesn't always mean simpler. Your first example was succinct, readable, and easily changeable, without being unnecessarily complex.

a.map { |s| "'#{s}'" }.join(' ')

edited Jul 2, 2013 at 1:05

answered Aug 20, 2010 at 4:30

captainpete

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Comments

statenjason · Accepted Answer · 2015-03-26 18:52:42Z

14

Try out

"'#{a.join("' '")}'"

Or if golfing

?'+a*"' '"+?'

edited Mar 26, 2015 at 18:52

answered Aug 19, 2010 at 15:06

statenjason

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3 Comments

Bernard Over a year ago

All those quotes are finicky but you've got the best answer so far.

Chuck Over a year ago

I'm not saying this is bad, but it doesn't exactly read naturally either. It's the sort of thing that will make even an experienced Rubyist go "Huh?" at first glance.

captainpete Over a year ago

Interesting golf putt!

Rostyslav Dzinko · Accepted Answer · 2012-08-21 08:48:01Z

1

Try this:

"'" + a.join("' '") + "'"

edited Aug 21, 2012 at 8:48

Rostyslav Dzinko

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answered Aug 19, 2010 at 15:09

bensie

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Comments

John La Rooy · Accepted Answer · 2010-08-20 15:54:27Z

0

"'"+a*"' '"+"'"

or

"'#{a*"' '"}'"

or

a.to_s[1...-1].gsub /",?/,"'"

edited Aug 20, 2010 at 15:54

answered Aug 20, 2010 at 15:43

John La Rooy

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