Ruby on rails Rails散列按其值进行组合
我有一个Ruby on rails Rails散列按其值进行组合,ruby-on-rails,ruby,Ruby On Rails,Ruby,我有一个问题列表,我需要将它们分开。关系是 Question_set has_many questions BookVolume has_many questions Subject has_many book_volumes Publisher has_many subjects Section has_many :questions 现在,我只将问题及其相关模型id,名称放入数组中的散列 data = [] question_set.questions.each do |q| d
问题
列表,我需要将它们分开。关系是
Question_set has_many questions
BookVolume has_many questions
Subject has_many book_volumes
Publisher has_many subjects
Section has_many :questions
现在,我只将问题
及其相关模型id
,名称
放入数组中的散列
data = []
question_set.questions.each do |q|
data << {publisher: {id: q.publisher.id, name: q.publisher.name}, subject: {id: q.book_volume.subject.id, name: q.book_volume.subject.name}, volume: {id: q.book_volume_id, name: q.book_volume.name}, chapter: [{id: q.section_id, name: q.section.name}]}
end
但是,如果它们得到相同的出版商
,主题
和卷
因此,在这种情况下,它将是
>>data
[
{
:publisher => {
:id => 96,
:name => "P1"
},
:subject => {
:id => 233,
:name => "S1"
},
:volume => {
:id => 1136,
:name => "V1"
},
:chapter => [
{
:id => 16155,
:name => "C2"
},
{
:id => 16158,
:name => "C2"
}
]
}
]
代码
def group_em(data)
data.group_by { |h| [h[:publisher], h[:subject], h[:volume]] }.
map do |k,v|
h = { publisher: k[0], subject: k[1], volume: k[2] }
h.update(chapters: v.each_with_object([]) { |f,a|
a << f[:chapter] }.flatten)
end
end
这里的数据
只包含两个散列,这些散列对于键:publisher
、:subject
和:volume
具有相同的值。这段代码允许数组具有任意数量的散列,并将它们按这三个键的值数组分组,为每个组生成一个散列。此外,键:chapters
的值是包含单个散列的数组,但该代码允许该数组包含多个散列。(如果该数组总是有一个哈希值,考虑生成<代码>的值:章节哈希本身,而不是包含哈希的数组)
解释
请参阅和(又名散列#合并!
)
步骤如下
h = data.group_by { |h| [h[:publisher], h[:subject], h[:volume]] }
#=> {
# [{:id=>96, :name=>"P1"},
# {:id=>233, :name=>"S1"},
# {:id=>1136, :name=>"V1"}
# ]=>[{:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"},
# :chapter=>[{:id=>16155, :name=>"C1"}]
# },
# {:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"},
# :chapter=>[{:id=>16158, :name=>"C2"}]
# }
# ]
# }
第一个键值对被传递到map
的块,并分配块变量
k,v = h.first
#=> [[{:id=>96, :name=>"P1"}, {:id=>233, :name=>"S1"}, {:id=>1136, :name=>"V1"}],
# [{:publisher=>{:id=>96, :name=>"P1"}, :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"}, :chapter=>[{:id=>16155, :name=>"C1"}]},
# {:publisher=>{:id=>96, :name=>"P1"}, :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"}, :chapter=>[{:id=>16158, :name=>"C2"}]}]]
k #=> [{:id=>96, :name=>"P1"}, {:id=>233, :name=>"S1"}, {:id=>1136, :name=>"V1"}]
v #=> [{:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"},
# :chapter=>[{:id=>16155, :name=>"C1"}]},
# {:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"},
# :chapter=>[{:id=>16158, :name=>"C2"}]}]
并进行了分块计算
h = { publisher: k[0], subject: k[1], volume: k[2] }
#=> {:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"}
# }
a = v.each_with_object([]) { |f,a| a << f[:chapter] }
#=> [[{:id=>16155, :name=>"C1"}], [{:id=>16158, :name=>"C2"}]]
b = a.flatten
#=> [{:id=>16155, :name=>"C1"}, {:id=>16158, :name=>"C2"}]
h.update(chapters: b)
#=> {:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"},
# :chapters=>[{:id=>16155, :name=>"C1"}, {:id=>16158, :name=>"C2"}]
# }
h={publisher:k[0],subject:k[1],volume:k[2]}
#=>{:publisher=>{:id=>96,:name=>“P1”},
#:subject=>{:id=>233,:name=>“S1”},
#:volume=>{:id=>1136,:name=>“V1”}
# }
a=v.each_with_object([]){f,a|a[{{:id=>16155,:name=>C1}],{:id=>16158,:name=>C2}]]
b=a.变平
#=>[{:id=>16155,:name=>C1},{:id=>16158,:name=>C2}]
h、 更新(第二章)
#=>{:publisher=>{:id=>96,:name=>“P1”},
#:subject=>{:id=>233,:name=>“S1”},
#:volume=>{:id=>1136,:name=>“V1”},
#:chapters=>[{:id=>16155,:name=>C1},{:id=>16158,:name=>C2}]
# }
可以用来代替Hash#update
如何:
data = {}
question_set.questions.each do |q|
key = "#{q.publisher.id}:#{q.book_volume.subject.id}:#{q.book_volume_id}"
if data[key].present?
data[key][:chapter] << {id: q.section_id, name: q.section.name}
else
data[key] = {publisher: {id: q.publisher.id, name: q.publisher.name}, subject: {id: q.book_volume.subject.id, name: q.book_volume.subject.name}, volume: {id: q.book_volume_id, name: q.book_volume.name}, chapter: [{id: q.section_id, name: q.section.name}]}
end
end
result = data.values
data={}
问题|集合。问题。每个都做| q|
key=“#{q.publisher.id}:#{q.book_volume.subject.id}:#{q.book_volume_id}”
如果数据[键]。是否存在?
data[key][:chapter]我不确定你是否说过让arr等于散列数组(上面的第一个数组),我们可以这样做。
这是否意味着arr=data
?如果变量data
包含该数组,是的。当你给出一个例子时,为每个输入对象分配一个变量(例如,data=[{:publisher=>…]
)。这样,读者就可以在注释和答案中引用这些变量(此处仅为数据
),而无需对其进行定义。您可以编辑您的问题来完成此操作。我已定义了变量名数据=[]
,然后在我的问题中放入散列
,你是这个意思吗?我明白了。我的错误。谢谢,它对我非常有用!在最后一行,result=data.values,它变成了一个数组。哦,我错过了它,这真是一个惊人的方法!
h = { publisher: k[0], subject: k[1], volume: k[2] }
#=> {:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"}
# }
a = v.each_with_object([]) { |f,a| a << f[:chapter] }
#=> [[{:id=>16155, :name=>"C1"}], [{:id=>16158, :name=>"C2"}]]
b = a.flatten
#=> [{:id=>16155, :name=>"C1"}, {:id=>16158, :name=>"C2"}]
h.update(chapters: b)
#=> {:publisher=>{:id=>96, :name=>"P1"},
# :subject=>{:id=>233, :name=>"S1"},
# :volume=>{:id=>1136, :name=>"V1"},
# :chapters=>[{:id=>16155, :name=>"C1"}, {:id=>16158, :name=>"C2"}]
# }
data = {}
question_set.questions.each do |q|
key = "#{q.publisher.id}:#{q.book_volume.subject.id}:#{q.book_volume_id}"
if data[key].present?
data[key][:chapter] << {id: q.section_id, name: q.section.name}
else
data[key] = {publisher: {id: q.publisher.id, name: q.publisher.name}, subject: {id: q.book_volume.subject.id, name: q.book_volume.subject.name}, volume: {id: q.book_volume_id, name: q.book_volume.name}, chapter: [{id: q.section_id, name: q.section.name}]}
end
end
result = data.values