Outputting the values of an array given an array of indexes

Question

Given an array such as words = ["hello", ", ", "world", "!"], I am required to manipulate the elements which are made up of letters, so I will get a string in the end such as "*hello*, *world*!"

I have managed to retrieve the indexes from the array which contain letters using words.map.with_index { |element, index| index if element[[/a-zA-Z+/]] == element }.compact, which are [0, 2].

How could I use these indexes in a function, such that I could manipulate the words?

Unclear. Why do you collect the indices instead of directly collecting or modifying the words? — Stefan Pochmann
– Stefan Pochmann, Commented Dec 15, 2017 at 17:42
I think you are over thinking the problem a bit. Since the desired end result is a string it would make the most sense in this case to convert it to a String and then manipulate it using the methods String provides words.join.gsub(/\w+/) {|m| "*#{m}*"} — engineersmnky
– engineersmnky, Commented Dec 15, 2017 at 17:43
@engineersmnky Or slightly shorter using a variation of an answer Stefan provided here words.join.gsub(/\w+/,'*\0*'). — Sagar Pandya
– Sagar Pandya, Commented Dec 15, 2017 at 17:51

Mark Thomas · Accepted Answer · 2017-12-15 19:32:33Z

2

You don't need indexes for this. If you want to be able to put apply arbitrary logic to each array element, use map without indexes:

words.map{|w| w.gsub(/[a-zA-Z]+/,'*\0*')}.join

As others have pointed out, for the example you have given, you don't need to process the array at all, just join it into a string first. For example:

words.join.gsub(/[a-zA-Z]+/,'*\0*')

edited Dec 15, 2017 at 19:32

answered Dec 15, 2017 at 19:12

Mark Thomas

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2 Comments

Stefan Pochmann Over a year ago

Well, I'd say it fails for example for ["hello", ", ", "42", "!"] which it turns into "*hello*, *42*!", surrounding the number with asterisks. (That's one reason I didn't post it as answer myself but just as comment-reply to the previous comments)

Mark Thomas Over a year ago

Good point, I've changed it to use OP's regex. Hey, digits are word characters according to regex :)

Dyaniyal Wilson · Accepted Answer · 2017-12-15 17:36:00Z

0

Try using Regexp, that would make your job easy. You can manipulate the elements after fetching it in an array

words = ["hello", ", ", "world", "!"]
array = []
words.each do |a|
  array << a if /\w/.match(a)
end

puts array

hello
world

answered Dec 15, 2017 at 17:36

Dyaniyal Wilson

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1 Comment

Sagar Pandya Over a year ago

I think OP wants "*hello*, *world*!".

Cary Swoveland · Accepted Answer · 2017-12-16 00:32:03Z

0

words.reject { |word| word.match?(/\p{^L}/) }.
      map { |word| "*%s*" % word }.
      join(', ')
  #=> "*hello*, *world*"

answered Dec 16, 2017 at 0:32

Cary Swoveland

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