Question

I am trying to write a loop that takes in a nested array and makes a sub-array of two consecutive tuples at a time. The input array may be something like this

arr = [['A','B'],['C','D'],['E','F'],['G','H'],['I','J'],['K','L'],
      ['M','N'],['O','P']]

Output: ['A','B'],['C','D']
        ['E','F'],['G','H']
        ['I','J'],['K','L']
        ['M','N'],['O','P']

I have tried out various loops, like

arr.each_slice(2) do |k,m|
   new_arr=[k,m]
   puts new_arr
end 

and

 arr.each_slice(2) { |k,m| puts(k,m) }

What is wrong with this? In both the cases, the output is

A
B
C
D .....

Answer 1

That’s just how puts is treating arrays in ruby 1.9, it prints each element on a new line. The result is what you want, it just looks differently when printed 🙂 Try printing with .inspect, for example.

arr = [['A','B'],['C','D'],['E','F'],['G','H'],['I','J'],['K','L'],
      ['M','N'],['O','P']]

arr.each_slice(2) do |k,m|
   new_arr = [k,m]
   puts new_arr.inspect
end
# >> [["A", "B"], ["C", "D"]]
# >> [["E", "F"], ["G", "H"]]
# >> [["I", "J"], ["K", "L"]]
# >> [["M", "N"], ["O", "P"]]

---

http://www.ruby-doc.org/core-1.9.3/IO.html#method-i-puts

puts(obj, …) → nil

Writes the given objects to ios as with IO#print. Writes a record separator (typically a newline) after any that do not already end with a newline sequence. If called with an array argument, writes each element on a new line. If called without arguments, outputs a single record separator.

$stdout.puts("this", "is", "a", "test")

produces:

this
is
a
test