How to extract number from array of string? (I m using regex)

Question

I have a array of string

test= ["ChangeServer<br/>Test: 3-7<br/>PinCode:DFSFSDFB04008<br/>ShipCode:DFADFSDFSDM-000D3<br/>SomeCode:sdfsdf", "werwerwe", "adfsdfsd", 
"sdfsdfsdfsd<br/>Test: 9<br/>PinCode:ADFSDF4NS0<br/>ShipCode:FADFSDFD-9ZM170<br/>"]

I want to grab the number after Test: which in the above array of string are 3, 4, 5, 6, 7 ( range 3-7) and 9

Desired output:

["3","4","5","6","7","9"]

What I tried so far

test.join.scan(/(?<=Test: )[0-9]+/)
=> ["3", "7"]

How to deal with range?

Second test case:

    test= ["ChangeServer<br/>Test: 3-7<br/>PinCode:DFSFSDFB04008<br/>ShipCode:DFADFSDFSDM-000D3<br/>SomeCode:sdfsdf", "werwerwe", "adfsdfsd", 
"sdfsdfsdfsd<br/>Test: 9<br/>PinCode:ADFSDF4NS0<br/>ShipCode:FADFSDFD-9ZM170<br/>", "sdfsdfsdfsd<br/>Test: 15-18<br/>PinCode:ADFSDF4NS0<br/>ShipCode:FADFSDFD-9ZM170<br/>"]

Desired output:

["3","4","5","6","7","9","15","16","17","18"]

Do it step by step: 1) extract "3-7" and "9", 2) Figure out how to convert "3-7" to ['3','4','5','6','7'], 3) combine the results — Stefan
– Stefan, Commented Jun 28, 2017 at 17:01

Jordan Running · Accepted Answer · 2017-06-28 19:34:31Z

5

There are a lot of ways you could solve this. I'd probably do it this way:

test.flat_map do |s|
  _, m, n = *s.match(/Test:\s*(\d+)(?:-(\d+))?/)
  m ? (m..n||m).to_a : []
end

See it in action on repl.it: https://repl.it/JFwT/13

Or, more succinctly:

test.flat_map {|s| s.match(/Test:\s*(\d+)(?:-(\d+))?/) { $1..($2||$1) }.to_a }

https://repl.it/JFwT/11

edited Jun 28, 2017 at 19:34

answered Jun 28, 2017 at 17:22

Jordan Running

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6 Comments

Gerry Over a year ago

Interesting and neat solution! BTW, you could get the exact desired output (strings instead of numbers) removing to_i.

Stefan Over a year ago

Since the OP wants an array of strings, you could shorten it to m.upto(n || m).to_a

Jordan Running Over a year ago

@Gerry, Stefan: Thanks for your suggestions; I've updated my answer.

engineersmnky Over a year ago

I really enjoyed this answer especially the "succinct" version. So just for fun Benchmarks available at repl.it/JFwT/16

Jordan Running Over a year ago

@engineersmnky It was fun to write. I'm not surprised by the benchmark result. Array#join is pretty well-optimized.

|

Gerry · Accepted Answer · 2017-06-28 19:29:05Z

4

You could create a new Range for each range found (i.e N-N) using the splat operator (i.e. *) and combine the results, like this ¹:

test.join.scan(/(?<=Test: )[0-9-]+/)
         .flat_map { |r| Range.new(*r.split('-').values_at(0, -1)).to_a }
#=> ["3", "4", "5", "6", "7", "9"]

This will work for both examples.

¹ Notice the the added - next to 0-9 in the regex.

Is the a way where we can include both Test: 1 (with space between Test: and 1) and Test:1 (without space between Test: and 1)?

Yes, update your regex (change where space is placed) and add an additional map to get rid of those spaces:

test.join
    .scan(/(?<=Test:)[ 0-9-]+/)
    .map(&:strip)
    .flat_map { |r| Range.new(*r.split('-').values_at(0, -1)).to_a }

And here's shortened option using two captures in the regex, as suggested by Jordan.

test.join
    .scan(/Test:\s*(\d+)(?:-(\d+))?/)
    .flat_map { |m,n| (m..n||m).to_a }

edited Jun 28, 2017 at 19:29

answered Jun 28, 2017 at 16:36

Gerry

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10 Comments

Kavincat Over a year ago

Thank you but there is extra number 8 which shouldn't be there.

Kavincat Over a year ago

Is the a way where we can include both Test: 1(with space between Test: and 1) and Test:1 (without space between Test: and 1)?

Gerry Over a year ago

@iceツ I also thought of that, but Range.new need 2..3 arguments, so won't work for all cases.

Stefan Over a year ago

flat_map { |r| Range.new(*r.split('-').values_at(0, -1)).to_a } would work for both, a-b notation and single values.

Jordan Running Over a year ago

@Gerry I'm pretty happy with my answer without join, so you're welcome to it.

|

Aleksei Matiushkin · Accepted Answer · 2017-06-28 18:03:43Z

0

Just out of curiosity:

test.
  join.
  scan(/(?<=Test: )[\d-]+/).
  map { |e| e.gsub(/\A\d+\Z/) { |m| "#{m}..#{m}" }.gsub('-', '..') }.
  map(&method(:eval)).
  flat_map(&:to_a)

answered Jun 28, 2017 at 18:03

Aleksei Matiushkin

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