用缺失值填充哈希数组

Question

我正在尝试为ApexChart 构建一些热图细节图表。到目前为止，我得到了这个 Hash 数组，用于 3 个活动。

[{
  :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
  }
}]

在活动 3 中，我们只有 2 个月，即July 和November。

我的需要是填充每个哈希，所有缺失的日期，并用 0 作为值填充它们。我期待的结果是

[{
  :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
  }
}]

是的，September 是故意丢失的。我想实现这一目标的最好方法是每个月一个一个地检索；然后用缺失的月份填充每个数组；但我不知道如何实现这一点。

Answer 1

如果arr 是您的哈希数组，您可以分两步构造所需的数组。

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
  #       }
  #     }
  #   ] 

请参阅Enumerable#flat_map、Date::strptime、Array#minmax、Date#strftime、Array#product 和 Hash#merge。有关日期格式指令，另请参阅 DateTime#strptime。

注意在first_month和last_month的计算中，

[#<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"]

Answer 2

您可以通过类似的方法来实现这一点，方法是首先获取月份，然后修改在您的情况下为哈希的数组项：

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

您还可以创建一个新的Array，其中Hash 值使用默认值进行初始化：

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

Answer 3

尝试以下方法：

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] }] } }