Question

I’m looking for a way to parse ordinal numbers (first, second, third, etc) in Ruby and convert them to integers. Do you know of any libraries that do this?

Answer 1

I was half-way through asking this question when I realized that the chronic gem does this as part of the process of parsing dates. After installing the gem, you can convert ordinal numbers to integers pretty easily:

irb(main):001:0> require 'chronic'
=> true
irb(main):002:0> Chronic::Numerizer.numerize("eighty-fifth").to_i
=> 85

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Edit: Unfortunately, it seems that chronic doesn’t correctly parse the ordinal “second”:

irb(main):003:0> Chronic::Numerizer.numerize("twenty-second").to_i
=> 20

The reason for this is that chronic is designed to parse dates and times, and “second” could be either an ordinal number or a unit of time in that context. To solve this problem, you can monkey patch chronic‘s Numerizer class with this line:

Chronic::Numerizer::ORDINALS.insert(1, ['second', '2'])

Now it works:

irb(main):005:0> Chronic::Numerizer.numerize("eighty-second").to_i
=> 82

If you are actually using chronic for its intended purpose though, you probably won’t want to screw with its internals. In that case, you can copy the source code from Chronic::Numerizer into a new class and use that one instead. Don’t forget to add ['second', '2'] to the ORDINALS constant in the new class.