String matching regex syntax issue

Question

I am trying to write a method to pulls out every string that matches the criteria from a large text file:

Every element is separated by a comma
The first 5 elements could be any number from 1-59
The next 21 elements should be numbers from 1-5
The next 27 elements could be either true or false (no caps)
The final 5 elements are integers from 1-5

My code:

#this string should be returned by the regex matching
str="3,15,14,31,40,5,5,4,5,3,4,4,5,2,2,2,1,2,1,1,3,3,3,2,4,3,false,false,false,false,false,true,false,true,false,false,false,false,false,false,false,true,false,false,false,false,false,false,false,false,false,false,false,3,3,3,2,3"
matchResult=/[1-59]{5}[1-5]{21}[true|false]{27}[1-5]{5}/.match(str)
matchResult.each{|x| #this doesnt work....why?
    puts x
}

What is the correct way to print all matches? matchResult.each throws an error. I thought it returned an array of matches.
How can I adjust my regex to expect a comma between every value (not at the ends of the string)?

Avinash Raj · Accepted Answer · 2015-03-31 03:30:05Z

1

Put true or false inside a capturing group or non-capturing group like (?:true|false) so that it would match the exact true or false substring , this [true|false] will match a single character only whether it may be t or r or u or e or | ,....

> str="3,15,14,31,40,5,5,4,5,3,4,4,5,2,2,2,1,2,1,1,3,3,3,2,4,3,false,false,false,false,false,true,false,true,false,false,false,false,false,false,false,true,false,false,false,false,false,false,false,false,false,false,false,3,3,3,2,3"
> str.match(/^(?:[1-5]\d|[1-9])(?:,(?:[1-5]\d|[1-9])){4}(?:,[1-5]){21}(?:,(?:true|false)){27}(?:,[1-5]){5}$/)
=> #<MatchData "3,15,14,31,40,5,5,4,5,3,4,4,5,2,2,2,1,2,1,1,3,3,3,2,4,3,false,false,false,false,false,true,false,true,false,false,false,false,false,false,false,true,false,false,false,false,false,false,false,false,false,false,false,3,3,3,2,3">

edited Mar 31, 2015 at 3:30

answered Mar 31, 2015 at 3:08

Avinash Raj

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3 Comments

Rilcon42 Over a year ago

some of my strings might have a comma at the beginning. Is there a way to adjust the regex for that? I tried: (/^(?:[,]*)(?:[1-5]\d|[1-9])(?:,(?:[1-5]\d|[1-9])){4}(?:,[1-5]){21}(?:,(?:true|false)){27}(?:,[1-5]){5}$/) but that didnt work

Avinash Raj Over a year ago

how your string looks like?

Rilcon42 Over a year ago

str=",3,15,14,31,40,5,5,4,5,3,4,4,5,2,2,2,1,2,1,1,3,3,3,2,4,3,false,false,false,false,false,true,false,true,false,false,false,false,false,false,false,true,false,false,false,false,false,false,false,false,false,false,false,3,3,3,2,3"

Community · Accepted Answer · 2017-05-23 10:24:15Z

1

In regards to your first question:

"What is the correct way to print all matches? matchResult.each throws an error. I thought it returned an array of matches."

The Regex .match method doesn't return an array of matches; it returns either a match object (in this case, a string, since you're calling .match on a string) or nil if there are no matches (see docs here).

This means matchResult is a string, and you can't call .each on a string, which is why you're getting an error message. See this post for more info on .each & strings.

edited May 23, 2017 at 10:24

CommunityBot

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answered Mar 31, 2015 at 3:10

ktravers

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2 Comments

Rilcon42 Over a year ago

Thanks, you pointed me in the right direction. It turns out I had to use scan rather then match

ktravers Over a year ago

No problem, glad it helped. And using .scan instead makes sense. Nice job working that out.

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