Split an array into new arrays (each with a unique name) [duplicate] - ruby

Question

This question already has answers here:
How to dynamically create a local variable?
(4 answers)
Closed 7 years ago.
I'm trying to slice an array into equal sizes (rounded down) and save each section to respective variables.
The method each_slice has worked to grab n-sized blocks. However I can't think of a way to:
iterate over the each's blocks' "sub index"
create a new array for each and give each a unique name.
letters = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n"]
def groups_of_five(array)
split_array = array.each_slice(5).to_a
#something like the following:
#array(n) = Array[split_array.each {|x| x}]
end
end
The output I'm hoping for:
groups_of_five(letters)
=> array1: ["a,"b","c","d","e"]
=> array2: ["f","g","h","i","j"]
=> array3: ["k","l","m","n"]

Answer 1

Combine each_slice with with_index and you'll have everything you need:
letters.each_slice(5).with_index(1) do |group, index|
puts "array#{index}: #{group.inspect}"
end
Output is:
array1: ["a", "b", "c", "d", "e"]
array2: ["f", "g", "h", "i", "j"]
array3: ["k", "l", "m", "n"]
It's no longer possible to set local variable dynamically in Ruby versions greather than 1.8, so if you want to assign to variables it will have to be instance variables or you could output a Hash.
The following will create instance variables:
def groups_of_five(array)
array.each_slice(5).with_index(1) do |group, index|
instance_variable_set "#array#{index}".to_sym, group
end
end
groups_of_five(letters)
puts #array1 #=> ["a", "b", "c", "d", "e"]
puts #array2 #=> ["f", "g", "h", "i", "j"]
puts #array3 #=> ["k", "l", "m", "n"]
Or this will output a Hash:
def groups_of_five(array)
hash = {}
array.each_slice(5).with_index(1) do |group, index|
hash["array#{index}".to_sym] = group
end
hash
end
hash = groups_of_five(letters)
puts hash[:array1] #=> ["a", "b", "c", "d", "e"]
puts hash[:array2] #=> ["f", "g", "h", "i", "j"]
puts hash[:array3] #=> ["k", "l", "m", "n"]

Answer 2

If you are looking for a hash structure to return from groups_of_five(letters), here's the solution
def groups_of_five(array)
split_array = letters.each_slice(5).to_a
split_array.reduce({}){ |i,a|
index = split_array.index(a) + 1
i["array#{index}"] = a; i
}
end
# groups_of_five(letters)
#=> {"array1"=>["a", "b", "c", "d", "e"], "array2"=>["f", "g", "h", "i", "j"], "array3"=>["k", "l", "m", "n"]}

Answer 3

You could do this:
def group_em(a,n)
arr = a.dup
(1..(arr.size.to_f/n).ceil).each_with_object({}) { |i,h|
h["array#{i}"] = arr.shift(n) }
end
group_em(letters,1)
#=> {"array1"=>["a"], "array2"=>["b"],...,"array14"=>["n"]}
group_em(letters,2)
#=> {"array1"=>["a", "b"], "array2"=>["c", "d"],...,"array7"=>["m", "n"]}
group_em(letters,5)
#=> {"array1"=>["a", "b", "c", "d", "e"],
# "array2"=>["f", "g", "h", "i", "j"],
# "array3"=>["k", "l", "m", "n"]}
A variant is:
def group_em(arr,n)
(1..(arr.size.to_f/n).ceil).zip(arr.each_slice(n).to_a)
.each_with_object({}) { |(i,a),h| h["array#{i}"]=>a) }
end