Sorting an array of string-integer identifiers (like "chapter3lesson11")

I want to sort my array:

p1q1
p1q10
p1q2

to this order:

p1q1
p1q2
p1q10

ie: By growing p integer, then by growing q integer.

I 开发者_如何学Goam trying with ids.sort { |id| id.to_i } constructs, but I am probably re-inventing the wheel... what's the most readable/simplest way to perform this sort?

The easiest way I can think of is this:

>> arr.sort_by { |id| id =~ /^p(\d+)q(\d+)$/ ; [$1.to_i, $2.to_i] }
=> ["p1q1", "p1q2", "p1q10"]

This should work with arbitrary depth, not just two levels:

ids.sort_by { |id| id.scan /\d+/ }

I would to something like this:

def p_q_str_to_num(str)
  str =~ /p(\d+)q(\d+)/
  ($1+$2).to_i
end

a = ["p1q1", "p1q10", "p1q2"]
a.sort {|x,y| p_q_str_to_num(x) <=> p_q_str_to_num(y)}

Returns:

["p1q1", "p1q2", "p1q10"]