For number n, I could only think of
array_of_digits = n.to_s.split('').map(&:to_i)
Is there any more elegant method?
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@itdoesntwork's `each_byte` method is interesting, but I think most Rubiests would go with what you have, though I think `string_of_digits = n.to_s.each_char.map(&:to_i)` is a small improvement because it doesn't create an intermediate array. – Cary Swoveland Apr 12 '15 at 19:13
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Not more elegant, but faster:
def digits(n)
(0..Math.log10(n).to_i).map { |dp| n / 10 ** dp % 10 }.reverse
end
Another fast one I just found (fastest)
def digits(n)
n.to_s.each_byte.map { |x| x - 48 }
end
Benchmarks:
user system total real
Split map 0.410000 0.000000 0.410000 ( 0.412397)
chars 0.100000 0.010000 0.110000 ( 0.104450)
each byte 0.070000 0.000000 0.070000 ( 0.068171)
Numerical 0.100000 0.000000 0.100000 ( 0.101828)
The code for benchmarking is here, by the way: https://gist.github.com/sid-code/9ad26dc4b509bfb86810
itdoesntwork
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2I was thinking split was slow too . . . want to compare with `n.to_s.chars.map(&:to_i)` ? – Neil Slater Apr 12 '15 at 17:57
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Yeah, I'd go for the chars one, it's fast and elegant, best of both worlds. – itdoesntwork Apr 12 '15 at 18:03
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Numerical gives you some insight though (I expect `Fixnum#to_s` has something similar internally). Good answer either way. – Neil Slater Apr 12 '15 at 18:04