Regex drops the last character in the string

Question

After working with a Regex supplied by Cary (thank you!), I realized it is dropping the last date in the string when I run it in IRB. Here is the code and the output. Can anyone tell me why this is happening and how to fix it?

require 'rubygems' 
require 'nokogiri' 
require 'open-uri' 

str = "September 19, 20, 25, 26, October 2, 3, 4, 10, November 3, 12, 17" 
dates=str.scan(/\D+(?:\d+,\s+)+/).map { |s| [ s[/[a-z]+/i], s.scan(/\d+/) ] } 

p dates

The output is the following. As you can see, November only returns 2 dates but there are 3 in the string. It drops November 17.

 [["September", ["19", "20", "25", "26"]], ["October", ["2", "3", "4", "10"]], ["November", ["3", "12"]]]

C:\RailsInstaller\Ruby1.9.3\nokogiri> –

I fixed the error in my [original answer](http://stackoverflow.com/questions/26086602/can-anyone-help-me-dry-this-regex/26087594#comment43610779_26087594) and also changed the approach, I think for the better. It is now `str.scan(/[A-Z][a-z]+|\d+/).each_with_object([]) { |e,b| e[0][/[A-Z]/] ? b << [e,[]] : b.last.last << e }`. — Cary Swoveland, Dec 21 '14 at 21:57

score 1 · Answer 1 · answered Dec 21 '14 at 19:22

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This should probably solve the problem:

dates=str.scan(/\D+(?:\d+(?:,\s+|$))+/).map { |s| [ s[/[a-z]+/i], s.scan(/\d+/) ] }

answered Dec 21 '14 at 19:22

davidrac

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Thanks everyone. Actually, Cary Swoveland's answer worked perfectly, but I don't know how to accept a comment. – Gary7 Dec 25 '14 at 13:08

Uri Agassi · Answer 2 · 2014-12-21T19:45:50.240

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The last string does not end with , \s+.

You need to create a case for the end of the string:

str = "September 19, 20, 25, 26, October 2, 3, 4, 10, November 3, 12, 17" 
dates=str.scan(/\D+(?:\d+(?:,\s+|$))+/).map { |s| [ s[/[a-z]+/i], s.scan(/\d+/) ] } 

p dates

edited Dec 21 '14 at 19:45

answered Dec 21 '14 at 19:22

Uri Agassi

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score 1 · Answer 3 · edited May 23 '17 at 12:12

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Make the ,\s+ portion of the regular expression optional: (?:,\s+)?. Put together:

str.scan(/\D+(?:\d+(?:,\s+)?)+/) ...

It uses a non-capturing group so it doesn't interfere with how the scan method works.

edited May 23 '17 at 12:12

Community

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answered Dec 21 '14 at 19:24

August

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Regex drops the last character in the string

3 Answers3