Ruby - Converting a mixed string into an array

Question

I'm working on a problem where I am given a "coded" message in the form of a string, and have to return the decoded message. This requires me to split a string of mixed characters and numbers into an array. So for example, if I got a string like this:

"0h"

I want to split it into an array like this:

[0, "h"]

But when I use .split I get

["0", "h"]

The solutions I have found only take into account strings that are all numbers, but not mixed strings. Is there a way to convert the strings that are numbers into numbers while retaining the characters?

Cary Swoveland · Accepted Answer · 2016-09-06 06:43:15Z

4

You can use String#scan with a regular expression.

str = "0hh1ghi22d"

str.scan(/\d+|\D+/).map { |s| s =~ /\d+/ ? s.to_i : s }
  #=> [0, "hh", 1, "ghi", 22, "d"]

or

str.each_char.map { |s| s =~ /\d/ ? s.to_i : s }
  #=> [0, "h", "h", 1, "g", "h", "i", 2, 2, "d"]

depending on requirements.

edited Sep 6, 2016 at 6:43

answered Sep 6, 2016 at 4:49

Cary Swoveland

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7 Comments

tadman Over a year ago

chars as the first part also works if individual characters are desired.

Cary Swoveland Over a year ago

@tadman, good suggestion, as the question is not clear on that. I did an edit.

Stefan Over a year ago

You can avoid matching \d+ twice by using capture groups: str.scan(/(\D+)|(\d+)/).map { |s, d| s || d.to_i } (note that I've changed the order of \D+ and \d+)

Cary Swoveland Over a year ago

@Stefan, that's lovely,but I don't understand why you needed to change the order of \d+ and \D+. Readers, if you don't follow Stefan's code, note that str.scan(/(\D+)|(\d+)/) #=> [[nil, "0"], ["hh", nil], [nil, "1"], ["ghi", nil], [nil, "22"], ["d", nil]].

quartzcrusher Over a year ago

Thank you! This worked great. Just so I know I understand what's happening since I'm really new at maps, it's passing each character to a block, seeing if the character is a number and if it is it converts it to an integer. Is that what /\d/ does? Just want to make sure I understand the logic of it. Thanks a lot for the help!

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user1934428 · Accepted Answer · 2016-09-06 04:49:41Z

1

If I understand you correctly, you want to have digits in the string end up as Fixnums in your array.

You can do this by adding a .map to your split:

... .map { |c| c =~ /\d/ ? c.to_i : c }

answered Sep 6, 2016 at 4:49

user1934428

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