Right way to extract multiple values from string using regex in ruby 1.8

Question

I'm relatively new to ruby and I'm trying to figure out the "ruby" way of extracting multiple values from a string, based on grouping in regexes. I'm using ruby 1.8 (so I don't think I have named captures).

I could just match and then assign $1,$2 - but I feel like there's got to be a more elegant way (this is ruby, after all).

I've also got something working with grep, but it seems hackish since I'm using an array and just grabbing the first element:

input="FOO: 1 BAR: 2"
foo, bar = input.grep(/FOO: (\d+) BAR: (\d+)/){[$1,$2]}[0]
p foo
p bar

I've tried searching online and browsing the ruby docs, but haven't been able to figure anything better out.

Lee Jarvis · Accepted Answer · 2012-07-25 14:02:16Z

5

Rubys String#match method returns a MatchData object with the method captures to return an Array of captures.

>> string = "FOO: 1 BAR: 2"
=> "FOO: 1 BAR: 2"
>> string.match /FOO: (\d+) BAR: (\d+)/
=> #<MatchData "FOO: 1 BAR: 2" 1:"1" 2:"2">
>> _.captures
=> ["1", "2"]
>> foo, bar = _
=> ["1", "2"]
>> foo
=> "1"
>> bar
=> "2"

To Summarize:

foo, bar = input.match(/FOO: (\d+) BAR: (\d+)/).captures

answered Jul 25, 2012 at 14:02

Lee Jarvis

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2 Comments

zje Over a year ago

So something like foo, bar = input.match(/FOO: (\d+) BAR: (\d+)/).captures? Definitely more readable

Lee Jarvis Over a year ago

Nice timing, I literally just altered my original post with the same thing. Yep, that'll do it.

Michael Kohl · Accepted Answer · 2012-07-25 14:05:20Z

1

Either:

foo, bar = string.scan(/[A-Z]+: (\d+)/).flatten

or:

foo, bar = string.match(/FOO: (\d+) BAR: (\d+)/).captures

answered Jul 25, 2012 at 14:05

Michael Kohl

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Comments

Kibet Yegon · Accepted Answer · 2012-07-25 14:10:46Z

1

Use scan instead:

input="FOO: 1 BAR: 2"

input.scan(/FOO: (\d+) BAR: (\d+)/) #=> [["1", "2"]]

answered Jul 25, 2012 at 14:10

Kibet Yegon

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