How to sort given array list?

Question

list = ["HM00", "HM01", "HM010", "HM011", "HM012", "HM013", "HM014", "HM015", "HM016", "HM017", "HM018", "HM019", "HM02", "HM020", "HM021", "HM022", "HM023", "HM024", "HM025", "HM026", "HM027", "HM028", "HM029", "HM03", "HM030", "HM031", "HM032", "HM033", "HM034", "HM035", "HM036", "HM037", "HM038", "HM039", "HM04", "HM040", "HM041", "HM042", "HM043", "HM044", "HM045", "HM046", "HM047", "HM05", "HM06", "HM07", "HM08", "HM09"]

I want the display the results as ["HM00","HM01","HM002"...] but using sort method it is giving the below results

["HM00", "HM01", "HM010", "HM011", "HM012", "HM013", "HM014", "HM015", "HM016", "HM017", "HM018", "HM019", "HM02"]

Do all the values contain 'HM' or you might have other values too ? — Roc Khalil
– Roc Khalil, Commented Apr 11, 2019 at 8:01
You're getting that result because your array items are sorted alphanumerically. — user3574603
– user3574603, Commented Apr 11, 2019 at 8:08

Ursus · Accepted Answer · 2019-04-11 08:04:52Z

5

If every element has a number at the end

list.sort_by { |item| item.scan(/\d*$/).first.to_i }

match that number at the end, take the first one (because scan gives you an array of results), convert it to an integer

simpler

list.sort_by { |item| item[/\d*$/].to_i }

[] already takes the first match

answered Apr 11, 2019 at 8:04

Ursus

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G. Allen Morris III · Accepted Answer · 2019-04-15 11:17:48Z

0

There is a more general solution that will work with most strings that contain groups of numbers

number = /([+-]{0,1}\d+)/;

strings = [ '2', '-2', '10', '0010', '010', 'a', '10a', '010a', '0010a', 'b10', 'b2', 'a1b10c20', 'a1b2.2c2' ]

p strings.sort_by { |item| [item.split(number).each_slice(2).map {
  |x| x.size == 1 ? [ x[0], '0' ] : [ x[0], x[1] ] }].map {|y| ret = y.inject({r:[],x:[]}) { |s, z| s[:r].push [ z[0], z[1].to_r]; s[:x].push z[1].size.to_s; s }; ret[:r] + ret[:x] }.flatten
}

You can adjust number to match the types of numbers you want to use: integers, floating point, etc.

There is some extra code to sort equal numbers by length so that '10' comes before '010'.

answered Apr 15, 2019 at 11:17

G. Allen Morris III

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