求ruby散列值的和
我试图对ruby哈希中的值求和,但使用inject或reduce都不会返回正确的答案。似乎这些方法正在覆盖存储的当前值,而不是对它们求和 我的哈希如下所示:求ruby散列值的和,ruby,hash,reduce,inject,Ruby,Hash,Reduce,Inject,我试图对ruby哈希中的值求和,但使用inject或reduce都不会返回正确的答案。似乎这些方法正在覆盖存储的当前值,而不是对它们求和 我的哈希如下所示: @test = [ {"total"=>18, "type"=>"buy", "date"=>Thu, 21 Nov 2013, "instrument_code"=>"food"}, {"total"=>92, "type"=>"buy", "date"=>Thu, 14 Nov 2013
@test = [
{"total"=>18, "type"=>"buy", "date"=>Thu, 21 Nov 2013, "instrument_code"=>"food"},
{"total"=>92, "type"=>"buy", "date"=>Thu, 14 Nov 2013, "instrument_code"=>"food"},
{"total"=>12, "type"=>"buy", "date"=>Wed, 20 Nov 2013, "instrument_code"=>"drink"},
{"total"=>1, "type"=>"buy", "date"=>Mon, 11 Nov 2013, "instrument_code"=>"food"}
]
{"drink"=>12.0, "food"=>110}
以下是我失败的注入代码:
def additions_per_security
@test.group_by { |i| i.type }.each do |key, value|
if key == "buy"
value.group_by{ |i| i.date }.each do |key, value|
@sortable_additions[key] = value
end
@sorted_additions = @sortable_additions.sort_by { |key,value| key }
@sorted_additions.shift
@additions_per_security = Hash[@sorted_additions.map { |key, value|
[key, value]
}]
@additions_per_security.each do |key, value|
value.group_by { |i| i.instrument_code }.each do |key, value|
@additions_security[key] = value.inject(0){ |result, transaction|
(result += transaction.total)
}
end
end
end
end
return @additions_security
end
def additions_per_security
@@test.group_by { |i| i.type }.each do |key, value|
if key == "buy"
value.group_by { |i| i.date }.each do |key, value|
@sortable_additions[key] = value
end
@sorted_additions = @sortable_additions.sort_by { |key,value| key }
@sorted_additions.shift
@additions_per_security = Hash[@sorted_additions.map { |key, value|
[key, value]
}]
@additions_per_security.each do |key, value|
value.group_by { |i| i.instrument_code }.each do |key, value|
@additions_security[key] = value.map { |p| p.total }.reduce(0,:+)
end
end
end
end
return @additions_security
end
下面是我失败的reduce代码:
def additions_per_security
@test.group_by { |i| i.type }.each do |key, value|
if key == "buy"
value.group_by{ |i| i.date }.each do |key, value|
@sortable_additions[key] = value
end
@sorted_additions = @sortable_additions.sort_by { |key,value| key }
@sorted_additions.shift
@additions_per_security = Hash[@sorted_additions.map { |key, value|
[key, value]
}]
@additions_per_security.each do |key, value|
value.group_by { |i| i.instrument_code }.each do |key, value|
@additions_security[key] = value.inject(0){ |result, transaction|
(result += transaction.total)
}
end
end
end
end
return @additions_security
end
def additions_per_security
@@test.group_by { |i| i.type }.each do |key, value|
if key == "buy"
value.group_by { |i| i.date }.each do |key, value|
@sortable_additions[key] = value
end
@sorted_additions = @sortable_additions.sort_by { |key,value| key }
@sorted_additions.shift
@additions_per_security = Hash[@sorted_additions.map { |key, value|
[key, value]
}]
@additions_per_security.each do |key, value|
value.group_by { |i| i.instrument_code }.each do |key, value|
@additions_security[key] = value.map { |p| p.total }.reduce(0,:+)
end
end
end
end
return @additions_security
end
我有一个散列,我想对除了第一个日期之外的所有键的总数求和
我目前得到以下信息:
{"drink"=>12.0, "food"=>92}
我的预期结果如下所示:
@test = [
{"total"=>18, "type"=>"buy", "date"=>Thu, 21 Nov 2013, "instrument_code"=>"food"},
{"total"=>92, "type"=>"buy", "date"=>Thu, 14 Nov 2013, "instrument_code"=>"food"},
{"total"=>12, "type"=>"buy", "date"=>Wed, 20 Nov 2013, "instrument_code"=>"drink"},
{"total"=>1, "type"=>"buy", "date"=>Mon, 11 Nov 2013, "instrument_code"=>"food"}
]
{"drink"=>12.0, "food"=>110}
提前感谢您的建议。我对您的
inject
代码进行以下观察:
- 所有变量都不需要是实例变量;局部变量(无
)就足够了李>@
应该是test.group_by{i | i.type}…
test.group_by{i | i[“type”]}…
应引发异常,因为尚未创建哈希李>@sortable\u additions[key]=value
删除散列的第一个元素并返回该元素,但没有变量接收它(例如,@sorted_additions.shift
)李>h=@sorted_additions.shift
显示将@sorted_additions转换为数组,然后返回到相同的哈希李>@additions_per_security=Hash[@sorted_additions.map{| key,value |[key,value]}]
require 'date'
date1 = Date.parse("Thu, 21 Nov 2013") # => #<Date: 2013-11-21 ((2456618j,0s,0n),+0s,2299161j)>
date2 = Date.parse("Thu, 14 Nov 2013") # => #<Date: 2013-11-14 ((2456611j,0s,0n),+0s,2299161j)>
date3 = Date.parse("Thu, 20 Nov 2013") # => #<Date: 2013-11-20 ((2456617j,0s,0n),+0s,2299161j)>
date4 = Date.parse("Thu, 11 Nov 2013") # => #<Date: 2013-11-11 ((2456608j,0s,0n),+0s,2299161j)>
现在我们计算我们需要什么
test_buy = test.select {|h| h["type"] == "buy"}
earliest = test_buy.min_by {|h| h["date"]}["date"]
# => #<Date: 2013-11-11 ((2456608j,0s,0n),+0s,2299161j)>
all_but_last = test.reject {|h| h["date"] == earliest}
# => [{"total"=>18, "type"=>"buy", "date"=>date1, "instrument_code"=>"food"},
{"total"=>92, "type"=>"buy", "date"=>date2, "instrument_code"=>"food"},
{"total"=>12, "type"=>"buy", "date"=>date3, "instrument_code"=>"drink"}]
请注意,此处和下方将显示date1
、date2
和date3
的值(例如,date1
将显示);我在这里使用了变量名作为占位符,以使其更具可读性。此外,所有具有h[“date”]=最早的的哈希值h
都将被拒绝(如果有多个)
我使用了一些临时变量,包括test\u buy
,最早的
,除最后一个之外的所有
,分组
,键
和arr
。您可以通过“链接”来消除其中一些。在这里,我将向您展示如何去除其中一些:
test_buy = test.select {|h| h["type"] == "buy"}
earliest = test_buy.min_by {|h| h["date"]}["date"]
grouped = test_buy.reject {|h| h["date"] == earliest}.group_by \
{|h| h["instrument_code"]}
Hash[grouped.keys.map {|k| [k, grouped[k].reduce(0) \
{|t,h| t + h["total"]}]}] # => {"food"=>110, "drink"=>12}
您可能认为这看起来很复杂,但在您获得Ruby的使用经验之后,它将看起来非常自然,并且易于阅读。但是,使用链接的程度是一种样式首选项。请尝试:
test = [
{"total"=>18, "type"=>"buy", "date"=>Thu, 21 Nov 2013, "instrument_code"=>"food"},
{"total"=>92, "type"=>"buy", "date"=>Thu, 14 Nov 2013, "instrument_code"=>"food"},
{"total"=>12, "type"=>"buy", "date"=>Wed, 20 Nov 2013, "instrument_code"=>"drink"},
{"total"=>1, "type"=>"buy", "date"=>Mon, 11 Nov 2013, "instrument_code"=>"food"}
]
except_first_date = test.sort_by {|i| i['date'] }
except_first_date.shift
result = except_first_date.inject({}) {|m,i| m[i["instrument_code"]] = m[i["instrument_code"]].to_f + i['total'] ; m }
# => {"food"=>110.0, "drink"=>12.0}
如果您有简单的键/值散列
{1 => 42, 2 => 42}.values.sum
=> 84
您的testhash是否乱七八糟;在reduce代码中,使用类变量进行testhash。您的方法的复杂性令人不安,没有人能够告诉您为什么reduce
失败。乔丹,你的第一个问题是@testhash
不是散列。如果将外部的{}
更改为[]
,它将是一个哈希数组;现在它不是一个Ruby对象。另外,reduce
和inject
是同义词。最好通过删除不必要的散列元素来简化和修复testhash。日期,特别是,是不相关的,但可能会导致并发症。拍-你是正确的,我错过了[]@testhash是我正在处理的哈希的简化版本。它只是展示了这个问题的相关关键价值。Cary日期字段在那里,因为我需要对所有值求和,除了第一个日期的值。我已经更新了行与行之间的哈希读数,您对“first date”的引用似乎被解释为“不计算最早值为date
(此处为@testhash中的最后一个哈希)的哈希值”。您还应该从名称@testhash
中删除“hash”。请编辑以澄清。是的,这是正确的。我只想要第一个日期之后的任何日期的值,这就是为什么我按“日期”进行分组,排序并删除(.shift)最早的日期这很有效!!非常感谢你。我会继续读你是如何处理的,直到我有更好的理解。我在那里有“type”字段,因为还有“sell”类型,我也需要排除它们。但根据你给我的,我相信我能解决这个问题。非常感谢你的帮助!!!我很高兴你觉得它很有用。您将看到我将“type”字段放回了。{1=>42,2=>42}.values.sum NoMethodError:undefined方法[42,42]:数组`{1=>42,2=>30}.values.inject(:+)