Ruby each_with_index offset

Question

Can I define the offset of the index in the each_with_index loop iterator? My straight forward attempt failed:

some_array.each_with_index{|item, index = 1| s         


        

Answer 1

offset = 2
some_array[offset..-1].each_with_index{|item, index| some_func(item, index+offset) }

Answer 2

Actually, Enumerator#with_index receives offset as an optional parameter:

[:foo, :bar, :baz].to_enum.with_index(1).each do |elem, i|
  puts "#{i}: #{elem}"
end

outputs:

1: foo
2: bar
3: baz

BTW, I think it is there only in 1.9.2.

Answer 3

I ran into it.

My solution not necessary is the best, but it just worked for me.

In the view iteration:

just add: index + 1

That's all for me, as I don't use any reference to those index numbers but just for show in a list.

Answer 4

This works in every ruby version:

%W(one two three).zip(1..3).each do |value, index|
  puts value, index
end

And for a generic array:

a.zip(1..a.length.each do |value, index|
  puts value, index
end

Answer 5

The following is succinct, using Ruby's Enumerator class.

[:foo, :bar, :baz].each.with_index(1) do |elem, i|
    puts "#{i}: #{elem}"
end

output

1: foo
2: bar
3: baz

Array#each returns an enumerator, and calling Enumerator#with_index returns another enumerator, to which a block is passed.

Answer 6

Ariel is right. This is the best way to handle this, and it's not that bad

ary.each_with_index do |a, i|
  puts i + 1
  #other code
end

That is perfectly acceptable, and better than most of the solutions I've seen for this. I always thought this was what #inject was for...oh well.