Is there a %w{ }--like way to create array of fixnums in Ruby?

Question

Is there a way to create an array of Fixnums using ruby's % notation?

It's obviously quite trivial to write, for example [edit: changed example to nonconsecutive digits]

digits = %w{4 8 15 16 23 42}.map{|d| d.to_i}

=> [4, 8, 15, 16, 23, 42]

but it bugs me and I'm wondering if there is a way to do it without the map. None of these sources mention such a possibility---am I out of luck?

What does %w(array) mean?

What is the %w "thing" in ruby?

Ruby Programming Syntax - the % notation

Another related question: http://stackoverflow.com/questions/4287503/where-in-the-ruby-language-is-q-w-etc-defined — Andrew Grimm, Oct 04 '11 at 22:09

Jonas Elfström · Accepted Answer · 2011-10-04T19:49:58.640

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Since the % notation seems to be one of those "bastard" Perl string handling inheritances in Ruby I strongly doubt it but you can save a couple of characters by

digits = %w{1 2 3 4 5 6 7 8 9 10}.map(&:to_i)

edited Oct 04 '11 at 19:49

answered Oct 04 '11 at 19:09

Jonas Elfström

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Ooh, I wasn't aware of that syntax possibility. Nice. – eulerz Oct 04 '11 at 19:15
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It's called Symbol#to_proc and the wonderful @raganwald / Reginald Braithwaite taught me about it back in 2007. http://weblog.raganwald.com/2007/10/stringtoproc.html It's part of Ruby 1.9 and I think it's been backported to 1.8 as well. – Jonas Elfström Oct 04 '11 at 19:26
I can confirm it exists in 1.8.7 even without Rails. – Andrew Grimm Oct 04 '11 at 21:44

Jacob Mattison · Answer 2 · 2011-10-04T20:14:38.237

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The % notation is specifically about strings, so that won't help you get any closer than the example you gave.

If the integers you care about are consecutive, you could use a Range object:

(1..10).to_a

edited Oct 04 '11 at 20:14

answered Oct 04 '11 at 19:11

Jacob Mattison

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+1, but shouldn't it be `(1..10).to_a`? Without parenthesis, `to_a` is sent to `10:Fixnum`. – Matheus Moreira Oct 04 '11 at 19:17

score 2 · Answer 3 · answered Oct 04 '11 at 19:59

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Am I missing something or does

digits = [4, 8, 15, 16, 23, 42]

=> [4, 8, 15, 16, 23, 42]

not do it?

Excellent choice of numbers, btw :)

answered Oct 04 '11 at 19:59

dantswain

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:-) and no, you're perfectly correct. That's the 'normal' way to do it. But all those commas! Such a pain! – eulerz Oct 06 '11 at 21:35

score 0 · Answer 4 · answered Oct 04 '11 at 19:09

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Array.new(10) {|i| i}

It's a way of doing it without map.

answered Oct 04 '11 at 19:09

lucapette

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Well, yes, in the case of my made-up-for-the-example array that works fine, but I was rather hoping for more of a... general solution. – eulerz Oct 04 '11 at 19:14

score 0 · Answer 5 · answered Oct 04 '11 at 22:07

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You could edit parse.y, which turns source code into Ruby, and then re-compile Ruby. I've never edited parse.y myself, but here's an amusing and awesome talk at RubyKaigi2011 about it.

answered Oct 04 '11 at 22:07

Andrew Grimm

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Is there a %w{ }--like way to create array of fixnums in Ruby?

5 Answers5