[julia-users] Comprehension (generator) with statement IF and the number of true

[Martin Florek]

Hi all,
I'm new in Julia and I'm doing refactoring. I have the following function:

function mapeBase_v1(A::Vector{Float64}, F::Vector{Float64})
  s = 0.0
  count = 0
  for i in 1:length(A)
    if(A[i] != 0.0)
      s += abs( (A[i] - F[i]) / A[i])
      count += 1
    end
  end

  s, count 

end   

I'm looking for a simpler variant which is as follows:

function mapeBase_v2(A::Vector{Float64}, F::Vector{Float64})
# A - actual target values
# F - forecasts (model estimations)

  s = sumabs((x - y) / x for (x, y) in zip(A, F) if x != 0) # Generator

  count = length(A) # ???
  s, countend


However with this variant can not determine the number of non-zero elements. I 
found option with length(A[A .!= 0.0]), but it has a large allocation. Please, 
someone knows a solution with generator, or variant v1 is very good choice?


Thanks in advance,
Martin