Converting Ruby array of array into a hash

Question

I have an array of arrays as below :

[
  ["2021-07-26T11:38:42.000+09:00", 1127167],
  ["2021-08-26T11:38:42.000+09:00", 1127170],
  ["2021-09-26T11:38:42.000+09:00", 1127161],
  ["2021-07-25T11:38:42.000+09:00", 1127177],
  ["2021-08-27T11:38:42.000+09:00", 1127104]
]

What i want to have as the output :

{
  "2021-July" => [["2021-07-26T11:38:42.000+09:00", 1127167],["2021-07-25T11:38:42.000+09:00", 1127177]], 
  "2021-August" => [["2021-08-26T11:38:42.000+09:00", 112717],["2021-08-27T11:38:42.000+09:00", 112710]],  
  "2021-September" => ["2021-09-26T11:38:42.000+09:00", 112716]
}

I want to create the hash key year-month format based on the date value in each array element. What would be the easiest way to do this?

sam · Accepted Answer · 2021-10-05 12:37:43Z

2

use group_by

date_array = [["2021-07-26T11:38:42.000+09:00", 1127167],["2021-08-26T11:38:42.000+09:00", 112717],["2021-09-26T11:38:42.000+09:00", 112716],["2021-07-25T11:38:42.000+09:00", 1127177],["2021-08-27T11:38:42.000+09:00", 112710]]
result = date_array.group_by{ |e| Date.parse(e.first).strftime("%Y-%B") }

answered Oct 5, 2021 at 12:37

sam

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Comments

Manjunath P · Accepted Answer · 2021-10-05 12:11:11Z

1

date_array = [["2021-07-26T11:38:42.000+09:00", 1127167],["2021-08-26T11:38:42.000+09:00", 112717],["2021-09-26T11:38:42.000+09:00", 112716],["2021-07-25T11:38:42.000+09:00", 1127177],["2021-08-27T11:38:42.000+09:00", 112710]]

result_date_hash = Hash.new([])

date_array.each do |date|
  formatted_date = Date.parse(date.first).strftime("%Y-%B")
  result_date_hash[formatted_date] += date
end

Output:

puts result_date_hash 
 => 
{"2021-July"=>["2021-07-26T11:38:42.000+09:00", 1127167, "2021-07-25T11:38:42.000+09:00", 1127177],
 "2021-August"=>["2021-08-26T11:38:42.000+09:00", 1127170, "2021-08-27T11:38:42.000+09:00", 1127104],
 "2021-September"=>["2021-09-26T11:38:42.000+09:00", 1127161]}

edited Oct 5, 2021 at 12:11

answered Oct 5, 2021 at 11:53

Manjunath P

4333 silver badges10 bronze badges

2 Comments

Sergio Tulentsev Over a year ago

Looks like it could be achieved by a group_by one-liner

mu is too short Over a year ago

Careful, result_date_hash = Hash.new([]) is almost never what you want, that only works here because you use a += e to add elements to the arrays and += makes copies of a. You really should say result_date_hash = Hash.new { |h, k| h[k] = [] }.

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