Sum of arrays of different size [closed] - ruby-on-rails

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I have an array, whose elements are arrays of different sizes, say:
[[45, 96, 0.0, 96, 96, 96, 0.0], [04, 55, 06, 55, 04, 04, 02, 55]]
I want to find the sum of the two arrays, i.e.,
[49, 151, ...]

Answer 1

You can use something like this:
a.flat_map{|x| x.in_groups_of(a.max_by(&:size).size, 0)}.transpose.map(&:sum)
Or this:
a.max_by(&:size).map.with_index{|_, i| a.sum{|x| x[i]||0}}

Answer 2

Not very pretty, but works:
>> a = [[45, 96, 0.0, 96, 96, 96, 0.0], [04, 55, 06, 55, 04, 04, 02, 55]]
=> [[45, 96, 0.0, 96, 96, 96, 0.0], [4, 55, 6, 55, 4, 4, 2, 55]]
>> sorted_a = a.sort_by(&:size).reverse
=> [[4, 55, 6, 55, 4, 4, 2, 55], [45, 96, 0.0, 96, 96, 96, 0.0]]
>> zipped_a = sorted_a.first.zip(sorted_a.last)
=> [[4, 45], [55, 96], [6, 0.0], [55, 96], [4, 96], [4, 96], [2, 0.0], [55, nil]]
>> zipped_a.map{ |arr| arr.map{ |v| v || 0 } }.map(&:sum)
=> [49, 151, 6.0, 151, 100, 100, 2.0, 55]
First you have to sort the array starting the longest for zip to work properly. Zipping will then create nil values in the redundant values of the shorter arrays. So the next step is to replace these nils to zeroes (using the nested map) and finally you can sum the values.

Answer 3

You can try this way also
k =[]
for i in 0..ar.max_by(&:size).length-1 do
k << ar.map { |x| [x[i]] }
end
k.map(&:flatten).map{|a| a.compact.sum}
=> [49, 151, 6.0, 151, 100, 100, 2.0, 55]

Answer 4

a = [[45, 96, 0, 96, 96, 96, 0],
[ 4, 55, 6, 55, 4, 4, 2, 55]]
Array.new(a.max_by(&:size).size) { |i| a.reduce(0) { |t,e| t+e[i].to_i } }
#=>[49, 151, 6, 151, 100, 100, 2, 55]
Note that nil.to_i #=> 0 (ref).
Another example:
a = [[1], [2,3,4], [5,6]]
Array.new(a.max_by(&:size).size) { |i| a.reduce(0) { |t,e| t+e[i].to_i } }
#=> [8,9,4]