Fill an array of hash with missing values

user_3912805 0
Viewed 397

I'm trying to build some Heatmap specifics charts for ApexChart. So far, I got this Array of Hash, for 3 activities.

[{
  :name => "Activity 1",
  :data => {
    "May 2020" => 37, "June 2020" => 17, "July 2020" => 9, "August 2020" => 18
  }
}, {
  :name => "Activity 2",
  :data => {
    "May 2020" => 3
  }
}, {
  :name => "Activity 3",
  :data => {
    "July 2020" => 5, "November 2020" => 11
  }
}]

On Activity 3, we got only 2 months which are, July and November.

My needs would be to fill for each Hash, all missing date, and filling them with 0 as value. My awaited results would be

[{
  :name => "Activity 1",
  :data => {
    "May 2020" => 37, "June 2020" => 17, "July 2020" => 9, "August 2020" => 18, "November 2020" => 0
  }
}, {
  :name => "Activity 2",
  :data => {
    "May 2020" => 3, "June 2020" => 0, "July 2020" => 0, "August 2020" => 0, "November 2020" => 0
  }
}, {
  :name => "Activity 3",
  :data => {
    "May 2020" => , "June 2020" => 0, "July 2020" => 5, "August 2020" => 0, "November 2020" => 11
  }
}]

Yes, September is missing on purpose. I suppose the best way to achieve this would be to retrieve every months, one by one; Then to fill each arrays with the missing months; But I don't know how to achieve this.

apexcharts ruby-on-rails ruby
3 Answers

You can achieve this by something similar by first fetching the months and then modifying the array items which are Hashes in your case:

months = data.flat_map { |d| d[:data].keys }.to_set
data.each do |d|
  months.each do |month|
    d[:data][month] = 0 unless d[:data].key?(month)
  end
end

What you could also do is to create a new Array where the Hash values are initialized with a default value:

data_with_default = data.map do |d|
  {
    name: d[:name],
    data: Hash.new(0).update(d[:data])
  }
end
user_2212130

If arr is your array of hashes, you could construct the desired array in two steps.

require 'date'

date_fmt = "%B %Y"
first_month, last_month = arr.flat_map do |g|
  g[:data].keys
end.map { |s| Date.strptime(s, date_fmt) }.minmax
  #=> [#<Date: 2020-05-01 ((2458971j,0s,0n),+0s,2299161j)>,
  #    #<Date: 2020-11-01 ((2459155j,0s,0n),+0s,2299161j)>] 

h = (first_month..last_month).map do |d|
  d.strftime(date_fmt)
end.product([0]).to_h
  #=> {"May 2020"=>0, "June 2020"=>0, "July 2020"=>0, "August 2020"=>0,
  #    "September 2020"=>0, "October 2020"=>0, "November 2020"=>0} 

arr.map { |g| g.merge(:data => h.merge(g[:data])) }
  #=> [
  #     {
  #       :name=>"Activity 1",
  #       :data=>{
  #         "May 2020"=>37, "June 2020"=>17, "July 2020"=>9,
  #         "August 2020"=>18, "September 2020"=>0,
  #         "October 2020"=>0, "November 2020"=>0
  #       }
  #     },
  #     {
  #       :name=>"Activity 2",
  #       :data=>{
  #         "May 2020"=>3, "June 2020"=>0, "July 2020"=>0,
  #         "August 2020"=>0, "September 2020"=>0,
  #         "October 2020"=>0, "November 2020"=>0
  #       }
  #     },
  #     {
  #       :name=>"Activity 3",
  #       :data=>{
  #         "May 2020"=>0, "June 2020"=>0, "July 2020"=>5,
  #         "August 2020"=>0, "September 2020"=>0,
  #         "October 2020"=>0, "November 2020"=>11
  #       }
  #     }
  #   ]

See Enumerable#flat_map, Date::strptime, Array#minmax, Date#strftime, Array#product and Hash#merge. See also DateTime#strptime for date formatting directives.

Note that in the calculation of first_month and last_month,

[#<Date: 2020-05-01 ((2458971j,0s,0n),+0s,2299161j)>,
 #<Date: 2020-11-01 ((2459155j,0s,0n),+0s,2299161j)>].
  map { |d| d.strftime(date_fmt) }
  #=> ["May 2020", "November 2020"]
user_2569700

Try the following:

a = [{
  :name => "Activity 1",
  :data => {
    "May 2020" => 37, "June 2020" => 17, "July 2020" => 9, "August 2020" => 18
  }
}, {
  :name => "Activity 2",
  :data => {
    "May 2020" => 3
  }
}, {
  :name => "Activity 3",
  :data => {
    "July 2020" => 5, "November 2020" => 11
  }
}]

months = ['May 2020', 'June 2020', 'July 2020', 'August 2020', 'November 2020']

puts a.map { |h| { name: h[:name], data: Hash[months.map { |m| [m, h[:data][m] ? h[:data][m] : 0] }] } }
user_8879470
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