Arrays 使用ruby中不同哈希数组中的元素创建哈希_Arrays_Ruby_Hash

Arrays 使用ruby中不同哈希数组中的元素创建哈希

arrays ruby hash

Arrays 使用ruby中不同哈希数组中的元素创建哈希,arrays,ruby,hash,Arrays,Ruby,Hash,在一次训练营练习中，我们获得了以下阵列： library = [ { "title" => "Hitchhiker's Guide", "Author" => "Douglas Adams", "categories" => [ "comedy", "fiction", "british"] }, { "title" => "Pride and Prejudice", "Author" => "Jane Au

在一次训练营练习中，我们获得了以下阵列：

library = [
  {
    "title" => "Hitchhiker's Guide", 
    "Author" => "Douglas Adams", 
    "categories" => [ "comedy", "fiction", "british"]
  },
  {
    "title" => "Pride and Prejudice", 
    "Author" => "Jane Austen", 
    "categories" => [ "morality", "fiction", "society", "british"]
  },
  {
    "title" => "Search Inside Yourself", 
    "Author" => "Chade-Meng Tan", 
    "categories" => [ "self improvement", "non-fiction", "mindfulness", "business"]
  },
  {
    "title" => "Benjamin Franklin: An American Life", 
    "Author" => "Walter Isaacson", 
    "categories" => [ "non-fiction", "history", "founding fathers"]
  },
  {
    "title" => "Glengarry Glen Ross", 
    "Author" => "David Mamet", 
    "categories" => [ "play", "fiction", "drama"]
  }
]

我们需要创建一个新的散列，其中类别作为元素，标题作为值

我知道如何创建一个

类别\u散列

，但我不知道如何将标题附加到每个类别。这是我的密码：

category_hash = {}
sub_category = []

library.each do |book|
  book["categories"].each do |category|
    sub_category << category
  end
  sub_category.each do |index|
    category_hash[index] = "I'm not sure how to append the titles here"
  end
end

p category_hash

category_hash={}
子类别=[]
图书馆。每本书|
书籍[“类别”]。每一本书都有一个类别|
子类别您可以使用：
您可以使用：
这里有另一种方法，比@AndreyDeineko的答案效率低
library.map{|h| h.values_at("categories", "title")}.to_h

结果:
{
  ["comedy", "fiction", "british"]=>"Hitchhiker's Guide", 
  ["morality", "fiction", "society", "british"]=>"Pride and Prejudice",
  ["self improvement", "non-fiction", "mindfulness", "business"]=>"Search Inside Yourself",
  ["non-fiction", "history", "founding fathers"]=>"Benjamin Franklin: An American Life",
  ["play", "fiction", "drama"]=>"Glengarry Glen Ross"
}

{
  "comedy"=>"Hitchhiker's Guide",
  "fiction"=>"Glengarry Glen Ross",
  "british"=>"Pride and Prejudice",
  "morality"=>"Pride and Prejudice",
  "society"=>"Pride and Prejudice",
  "self improvement"=>"Search Inside Yourself",
  "non-fiction"=>"Benjamin Franklin: An American Life", 
  "mindfulness"=>"Search Inside Yourself",
  "business"=>"Search Inside Yourself",
  "history"=>"Benjamin Franklin: An American Life",
  "founding fathers"=>"Benjamin Franklin: An American Life",
  "play"=>"Glengarry Glen Ross",
  "drama"=>"Glengarry Glen Ross"
}

{
  "comedy"=>["Hitchhiker's Guide"],
  "fiction"=>["Hitchhiker's Guide", "Pride and Prejudice", "Glengarry Glen Ross"],
  "british"=>["Hitchhiker's Guide", "Pride and Prejudice"],
  "morality"=>["Pride and Prejudice"],
  "society"=>["Pride and Prejudice"],
  "self improvement"=>["Search Inside Yourself"],
  "non-fiction"=>["Search Inside Yourself", "Benjamin Franklin: An American Life"],
  "mindfulness"=>["Search Inside Yourself"],
  "business"=>["Search Inside Yourself"],
  "history"=>["Benjamin Franklin: An American Life"],
  "founding fathers"=>["Benjamin Franklin: An American Life"],
  "play"=>["Glengarry Glen Ross"],
  "drama"=>["Glengarry Glen Ross"]
}

如果您希望通过“category”
属性分发它（当然，这取决于数组中散列项的顺序；我假设您的意思是后面一个比前面一个优先）：
结果:
{
  ["comedy", "fiction", "british"]=>"Hitchhiker's Guide", 
  ["morality", "fiction", "society", "british"]=>"Pride and Prejudice",
  ["self improvement", "non-fiction", "mindfulness", "business"]=>"Search Inside Yourself",
  ["non-fiction", "history", "founding fathers"]=>"Benjamin Franklin: An American Life",
  ["play", "fiction", "drama"]=>"Glengarry Glen Ross"
}

{
  "comedy"=>"Hitchhiker's Guide",
  "fiction"=>"Glengarry Glen Ross",
  "british"=>"Pride and Prejudice",
  "morality"=>"Pride and Prejudice",
  "society"=>"Pride and Prejudice",
  "self improvement"=>"Search Inside Yourself",
  "non-fiction"=>"Benjamin Franklin: An American Life", 
  "mindfulness"=>"Search Inside Yourself",
  "business"=>"Search Inside Yourself",
  "history"=>"Benjamin Franklin: An American Life",
  "founding fathers"=>"Benjamin Franklin: An American Life",
  "play"=>"Glengarry Glen Ross",
  "drama"=>"Glengarry Glen Ross"
}

{
  "comedy"=>["Hitchhiker's Guide"],
  "fiction"=>["Hitchhiker's Guide", "Pride and Prejudice", "Glengarry Glen Ross"],
  "british"=>["Hitchhiker's Guide", "Pride and Prejudice"],
  "morality"=>["Pride and Prejudice"],
  "society"=>["Pride and Prejudice"],
  "self improvement"=>["Search Inside Yourself"],
  "non-fiction"=>["Search Inside Yourself", "Benjamin Franklin: An American Life"],
  "mindfulness"=>["Search Inside Yourself"],
  "business"=>["Search Inside Yourself"],
  "history"=>["Benjamin Franklin: An American Life"],
  "founding fathers"=>["Benjamin Franklin: An American Life"],
  "play"=>["Glengarry Glen Ross"],
  "drama"=>["Glengarry Glen Ross"]
}

这里有另一种方法，比@AndreyDeineko的答案效率低
library.map{|h| h.values_at("categories", "title")}.to_h

结果:
{
  ["comedy", "fiction", "british"]=>"Hitchhiker's Guide", 
  ["morality", "fiction", "society", "british"]=>"Pride and Prejudice",
  ["self improvement", "non-fiction", "mindfulness", "business"]=>"Search Inside Yourself",
  ["non-fiction", "history", "founding fathers"]=>"Benjamin Franklin: An American Life",
  ["play", "fiction", "drama"]=>"Glengarry Glen Ross"
}

{
  "comedy"=>"Hitchhiker's Guide",
  "fiction"=>"Glengarry Glen Ross",
  "british"=>"Pride and Prejudice",
  "morality"=>"Pride and Prejudice",
  "society"=>"Pride and Prejudice",
  "self improvement"=>"Search Inside Yourself",
  "non-fiction"=>"Benjamin Franklin: An American Life", 
  "mindfulness"=>"Search Inside Yourself",
  "business"=>"Search Inside Yourself",
  "history"=>"Benjamin Franklin: An American Life",
  "founding fathers"=>"Benjamin Franklin: An American Life",
  "play"=>"Glengarry Glen Ross",
  "drama"=>"Glengarry Glen Ross"
}

{
  "comedy"=>["Hitchhiker's Guide"],
  "fiction"=>["Hitchhiker's Guide", "Pride and Prejudice", "Glengarry Glen Ross"],
  "british"=>["Hitchhiker's Guide", "Pride and Prejudice"],
  "morality"=>["Pride and Prejudice"],
  "society"=>["Pride and Prejudice"],
  "self improvement"=>["Search Inside Yourself"],
  "non-fiction"=>["Search Inside Yourself", "Benjamin Franklin: An American Life"],
  "mindfulness"=>["Search Inside Yourself"],
  "business"=>["Search Inside Yourself"],
  "history"=>["Benjamin Franklin: An American Life"],
  "founding fathers"=>["Benjamin Franklin: An American Life"],
  "play"=>["Glengarry Glen Ross"],
  "drama"=>["Glengarry Glen Ross"]
}

如果您希望通过“category”
属性分发它（当然，这取决于数组中散列项的顺序；我假设您的意思是后面一个比前面一个优先）：
结果:
{
  ["comedy", "fiction", "british"]=>"Hitchhiker's Guide", 
  ["morality", "fiction", "society", "british"]=>"Pride and Prejudice",
  ["self improvement", "non-fiction", "mindfulness", "business"]=>"Search Inside Yourself",
  ["non-fiction", "history", "founding fathers"]=>"Benjamin Franklin: An American Life",
  ["play", "fiction", "drama"]=>"Glengarry Glen Ross"
}

{
  "comedy"=>"Hitchhiker's Guide",
  "fiction"=>"Glengarry Glen Ross",
  "british"=>"Pride and Prejudice",
  "morality"=>"Pride and Prejudice",
  "society"=>"Pride and Prejudice",
  "self improvement"=>"Search Inside Yourself",
  "non-fiction"=>"Benjamin Franklin: An American Life", 
  "mindfulness"=>"Search Inside Yourself",
  "business"=>"Search Inside Yourself",
  "history"=>"Benjamin Franklin: An American Life",
  "founding fathers"=>"Benjamin Franklin: An American Life",
  "play"=>"Glengarry Glen Ross",
  "drama"=>"Glengarry Glen Ross"
}

{
  "comedy"=>["Hitchhiker's Guide"],
  "fiction"=>["Hitchhiker's Guide", "Pride and Prejudice", "Glengarry Glen Ross"],
  "british"=>["Hitchhiker's Guide", "Pride and Prejudice"],
  "morality"=>["Pride and Prejudice"],
  "society"=>["Pride and Prejudice"],
  "self improvement"=>["Search Inside Yourself"],
  "non-fiction"=>["Search Inside Yourself", "Benjamin Franklin: An American Life"],
  "mindfulness"=>["Search Inside Yourself"],
  "business"=>["Search Inside Yourself"],
  "history"=>["Benjamin Franklin: An American Life"],
  "founding fathers"=>["Benjamin Franklin: An American Life"],
  "play"=>["Glengarry Glen Ross"],
  "drama"=>["Glengarry Glen Ross"]
}

如果希望一个类别中每本书的列表，并且一本书显示在多个类别中，则可以在将所有未知键设置为包含数组作为值时附加。然后，您只需迭代库中的每本书，并将其标题添加到它所属的每个类别的列表中：
# Pass the category hash a default proc, which will be called
# whenever a key it doesn't have is accessed. So, when you
# encounter a brand new category, it'll already be set up with
# an array
category_hash = Hash.new { |hash, key| hash[key] = [] }
library.each do |book|
  book['categories'].each do |category|
    # since we passed the default, no worrying, an array will be
    # there and we can just add our value into it
    category_hash[category] << book['title']
  end
end

puts category_hash

还有每个带有\u对象的\u
，因此您可以将其修改为
result = library.each.with_object(Hash.new { |hash, key| hash[key] = [] }) do |book, category_hash|
  book['categories'].each do |category|
    # since we passed the default, no worrying, an array will be
    # there and we can just add our value into it
    category_hash[category] << book['title']
  end
end
puts result

如果希望一个类别中每本书的列表，并且一本书显示在多个类别中，则可以在将所有未知键设置为包含数组作为值时附加。然后，您只需迭代库中的每本书，并将其标题添加到它所属的每个类别的列表中：
# Pass the category hash a default proc, which will be called
# whenever a key it doesn't have is accessed. So, when you
# encounter a brand new category, it'll already be set up with
# an array
category_hash = Hash.new { |hash, key| hash[key] = [] }
library.each do |book|
  book['categories'].each do |category|
    # since we passed the default, no worrying, an array will be
    # there and we can just add our value into it
    category_hash[category] << book['title']
  end
end

puts category_hash

还有每个带有\u对象的\u
，因此您可以将其修改为
result = library.each.with_object(Hash.new { |hash, key| hash[key] = [] }) do |book, category_hash|
  book['categories'].each do |category|
    # since we passed the default, no worrying, an array will be
    # there and we can just add our value into it
    category_hash[category] << book['title']
  end
end
puts result

这与其他答案略有不同
library = [
  {title: "Hitch Guide", by: "Doug", cats: ["comedy", "fiction", "british"]},
  {title: "P and P",     by: "Jane", cats: ["morality", "fiction", "british"]},
  {title: "Searchin'",   by: "Chad", cats: ["non-fiction", "morality", "gps"]},
  {title: "Crazy Ben",   by: "Walt", cats: ["non-fiction", "comedy", "dads"]}
]
  # => [{:title=>"Hitch Guide", :by=>"Doug", :cats=>["comedy", "fiction", "british"]},
  #     {:title=>"P and P", :by=>"Jane", :cats=>["morality", "fiction", "british"]},
  #     {:title=>"Searchin'", :by=>"Chad", :cats=>["non-fiction", "morality", "gps"]},
  #     {:title=>"Crazy Ben", :by=>"Walt", :cats=>["non-fiction", "comedy", "dads"]}]

library.each_with_object({}) do |g,h|
  title = g[:title]
  g[:cats].each { |c| (h[c] ||= []) << title }
end
  #=> {"comedy"=>["Hitch Guide", "Crazy Ben"],
  #    "fiction"=>["Hitch Guide", "P and P"],
  #    "british"=>["Hitch Guide", "P and P"],
  #    "morality"=>["P and P", "Searchin'"],
  #    "non-fiction"=>["Searchin'", "Crazy Ben"],
  #    "gps"=>["Searchin'"],
  #    "dads"=>["Crazy Ben"]}

库=[
{标题：“搭便车指南”，作者：“道格”，猫：[“喜剧”、“小说”、“英国”]}，
{标题：“P和P”，作者：“简”，猫：[“道德”、“小说”、“英国”]}，
{标题：“搜索”，作者：“乍得”，猫：[“非小说”、“道德”、“全球定位系统”]}，
{标题：“疯狂的本”，作者：“沃尔特”，猫：[“非小说”、“喜剧”、“爸爸”]}
]
#=>[{:title=>“搭便车指南”、：by=>“道格”、：cats=>[“喜剧”、“小说”、“英国”]，
#{：title=>“P和P”，：by=>“Jane”，：cats=>[“道德”、“小说”、“英国”]，
#{:title=>“Searchin'”，：by=>“Chad”，：cats=>[“非小说”、“道德”、“全球定位系统”]}，
#{:title=>“疯狂的本”、：by=>“沃尔特”、：cats=>[“非小说”、“喜剧”、“爸爸”]}]
库。每个带有_对象（{}）do | g，h的|
title=g[：title]
g[：猫]。每只{| c |（h[c]| |=[]）{“喜剧”=>[“搭车指南”，“疯狂本”]，
#“小说”=>[“挂接指南”，“P和P”]，
#“英国”=>[“挂接装置指南”，“P和P”]，
#“道德”=>[“P和P”，“搜索]，
#“非小说”=>[“搜索”，“疯狂本”]，
#“gps”=>[“搜索””，
#“爸爸”=>[“疯狂的本”]}
这是其他答案的一个细微变化
library = [
  {title: "Hitch Guide", by: "Doug", cats: ["comedy", "fiction", "british"]},
  {title: "P and P",     by: "Jane", cats: ["morality", "fiction", "british"]},
  {title: "Searchin'",   by: "Chad", cats: ["non-fiction", "morality", "gps"]},
  {title: "Crazy Ben",   by: "Walt", cats: ["non-fiction", "comedy", "dads"]}
]
  # => [{:title=>"Hitch Guide", :by=>"Doug", :cats=>["comedy", "fiction", "british"]},
  #     {:title=>"P and P", :by=>"Jane", :cats=>["morality", "fiction", "british"]},
  #     {:title=>"Searchin'", :by=>"Chad", :cats=>["non-fiction", "morality", "gps"]},
  #     {:title=>"Crazy Ben", :by=>"Walt", :cats=>["non-fiction", "comedy", "dads"]}]

library.each_with_object({}) do |g,h|
  title = g[:title]
  g[:cats].each { |c| (h[c] ||= []) << title }
end
  #=> {"comedy"=>["Hitch Guide", "Crazy Ben"],
  #    "fiction"=>["Hitch Guide", "P and P"],
  #    "british"=>["Hitch Guide", "P and P"],
  #    "morality"=>["P and P", "Searchin'"],
  #    "non-fiction"=>["Searchin'", "Crazy Ben"],
  #    "gps"=>["Searchin'"],
  #    "dads"=>["Crazy Ben"]}

库=[
{标题：“搭便车指南”，作者：“道格”，猫：[“喜剧”、“小说”、“英国”]}，
{标题：“P和P”，作者：“简”，猫：[“道德”、“小说”、“英国”]}，
{标题：“搜索”，作者：“乍得”，猫：[“非小说”、“道德”、“全球定位系统”]}，
{标题：“疯狂的本”，作者：“沃尔特”，猫：[“非小说”、“喜剧”、“爸爸”]}
]
#=>[{:title=>“搭便车指南”、：by=>“道格”、：cats=>[“喜剧”、“小说”、“英国”]，
#{：title=>“P和P”，：by=>“Jane”，：cats=>[“道德”、“小说”、“英国”]，
#{:title=>“Searchin'”，：by=>“Chad”，：cats=>[“非小说”、“道德”、“全球定位系统”]}，
#{:title=>“疯狂的本”、：by=>“沃尔特”、：cats=>[“非小说”、“喜剧”、“爸爸”]}]
库。每个带有_对象（{}）do | g，h的|
title=g[：title]
g[：猫]。每只{| c |（h[c]| |=[]）{“喜剧”=>[“搭车指南”，“疯狂本”]，
#“小说”=>[“挂接指南”，“P和P”]，
#“英国”=>[“挂接装置指南”，“P和P”]，
#“道德”=>[“P和P”，“搜索]，
#“非小说”=>[“搜索”，“疯狂本”]，
#“gps”=>[“搜索””，
#“爸爸”=>[“疯狂的本”]}
这是我通常的做法，我认为这是最简单的方法，尽管上面看到的每个带有对象的技巧也很简洁
new_hash = {}

library.each do |hash| 
  hash["categories"].each do |category|
    new_hash[category] ||= []
    new_hash[category] << hash["title"]
  end
end

new_hash={}
library.each do|hash|
散列[“类别”]。每个都做|类别|
新的_散列[类别]| |=[]
new_hash[category]这是我通常的做法，我认为这是最简单的方法，尽管上面看到的每个_with_object技巧也很简洁
new_hash = {}

library.each do |hash| 
  hash["categories"].each do |category|
    new_hash[category] ||= []
    new_hash[category] << hash["title"]
  end
end

new_hash={}
library.each do|hash|
散列[“类别”]。每个都做|类别|
新的_散列[类别]| |=[]
新的[category]您需要澄清（通过编辑）您所说的“…以类别作为元素…”是什么意思。首先，您指的是“键”而不是“元素”。您将看到并非所有答案都以相同的方式进行解释。到目前为止，有一个答案假设“categories”是与键关联的值“categories”
在库
的元素（散列）中；有两个答案假设“categories”是库
元素中“categories”的一个或多个值中包含的字符串（“喜剧”、“小说”、“英国”、“道德”、“社会”等）。我猜您是有意进行后一种解释的。您需要澄清（编辑）您所说的“…以类别作为元素…”是什么意思？首先，您指的是“键”而不是“元素”。您将看到并非所有答案都以相同的方式解释。到目前为止，有一个答案假设“类别”是与元素（哈希）中的键“类别”
关联的值对于库
；两个答案假设“categories”是库
元素（“喜剧”、“小说”、“英国”、“道德”、“社会”）中“categories”的一个或多个值中包含的字符串