I have this array:
array = ["1", "Hel", "6", "3", "lo" ] .
I want to output sum of the integers only, which is 10. How do I do that?
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3 Answers
just do :
array.inject(0) { |sum,n| sum + n.to_i } # => 10
#to_i will convert all the non integer strings to 0. But there is no problem, as for that over all summation will not be affected.
1 Comment
Gary S. Weaver
Most process efficient so far. Benchmarked and this is faster than
array.map(&:to_i).reduce(0, :+) (1.49s vs. 2.05s for 1000000 times for me)String#to_i will return 0 in your example so we can use it to map over all array elements.
array.map(&:to_i).reduce(0, :+)
3 Comments
Gary S. Weaver
Don't need to set initial for this problem, e.g. this produces same result:
array.map(&:to_i).reduce(:+). This is because initial defaults to the first item in the array, and even if to_i were to be called on a string or nil, both evaluate to 0, in Ruby 2.1 at least.
Kyle
@GaryS.Weaver it's there to provide a robust solution:
[].reduce(:+) # nil and [].reduce(0, :+) # 0Gary S. Weaver
Good catch! You're right, that was probably the intent.
Since Ruby 2.4 array has an Enumerable#sum method.
array.sum(&:to_i)
