ruby fill elements of an array into a set of nested arrays and remove duplicates

Question

I have the arrays months and monthly_doc_count_for_topic.

  months = ["2019-01-01", "2019-02-01", "2019-03-01", "2019-04-01"]
  monthly_doc_count_for_topic =  [
    ["foo","2019-02-01: 186904","2019-03-01: 196961"],
    ["bar","2019-01-01: 8876","2019-04-01: 8694"]
  ]
  goal = [ 
    ["foo","2019-02-01: 186904","2019-03-01: 196961","2019-01-01","2019-02-01","2019-03-01","2019-04-01"],
    ["bar","2019-01-01: 8876","2019-04-01: 8694","2019-01-01","2019-02-01","2019-03-01","2019-04-01"]
  ]

I'd like to fill in element of the array months into arrays inside monthly_doc_count_for_topic so it looks like array goal.

My attempt:

  monthly_doc_count_for_topic.map do |topic_set| 
    months.each { |month| topic_set << month }
  end

But I'm getting:

=> [
  [0] [
    [0] "2019-01-01",
    [1] "2019-02-01",
    [2] "2019-03-01",
    [3] "2019-04-01"
  ],
  [1] [
    [0] "2019-01-01",
    [1] "2019-02-01",
    [2] "2019-03-01",
    [3] "2019-04-01"
  ]
]

it's not appending the values from monthly_doc_count_for_topic instead replacing it with elements from array months. How can I modify my code to achieve the output like array goal? Thank you very much!

It appears you want monthly_doc_count_for_topic.map { |topic_set| topic_set + months }. — Cary Swoveland
– Cary Swoveland, Commented Jan 9, 2020 at 9:41
@CarySwoveland but this triples the elements of months into the nested sets — Sandra Cieseck
– Sandra Cieseck, Commented Jan 9, 2020 at 9:43
Oh, I was wrong! Your code works perfectly fine! @CarySwoveland Can you post this as an answer so that I can accept it as solution? Thank you very much!!! — Sandra Cieseck
– Sandra Cieseck, Commented Jan 9, 2020 at 9:52

StandardNerd · Accepted Answer · 2020-01-09 10:42:04Z

1

In your attempt replace

monthly_doc_count_for_topic.map

with

monthly_doc_count_for_topic.each

and it works perfectly fine:

goal = monthly_doc_count_for_topic.each do |topic_set|
  months.each { |month| topic_set << month }
end

But I'd prefer CarySwoveland's solution in the comment, it's less verbose:

monthly_doc_count_for_topic.map { |topic_set| topic_set + months }

edited Jan 9, 2020 at 10:42

answered Jan 9, 2020 at 10:13

StandardNerd

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