Enumerable#find_all除外

Question

我试图找出数组中的所有负数，但不包括某些类别中的对象。下面是数组的一个示例。

@transactions =
  [{"amount"=>-20, "name"=>"DEPOSIT", "category"=>["BENEFITS"], "category_id"=>"21007000"},
   {"amount"=>-0.8, "name"=>"XFER", "category"=>["Transfer", "Credit"], "category_id"=>"2106381"},
   {"amount"=>-20, "name"=>"DEPOSIT", "category"=>["Transfer", "Deposit"],
"category_id"=>"21007000"},
   {"amount"=>-1, "name"=>"XFER", "category"=>["Transfer", "Credit"],
"category_id"=>"21005000"},
   {"amount"=>300.80, "name"=>"XFER", "category"=>"Food", "category_id"=>"2106381"}]

到目前为止，我有这样的东西，但语法是错误的，它不起作用。我甚至不确定我是否可以在find_all块上使用“条件”。

items = @transactions.find_all ( { |t| t.fetch('amount') != t.fetch('amount').abs, :conditions => [ t.fetch('category_id') == '2106381' || t.fetch('category') == ["Benefits"] != ?, any? ]})

因此，找出所有带有负号的对象的数量，并从该列表中排除具有以下类别、id或类别名称的对象。

只有负值对象的输出，不具有名称或类别id "2106381“的好处。

Answer 1

你的问题不是特别清楚，但我怀疑这能做你想做的事：

@transactions.select do |t|
  t["amount"] < 0 &&
    t["category_id"] != "2106381" &&
    t["category"] != "Benefits"
end

或者，这更具有声明性(但效率略低)：

@transactions.select {|t| t["amount"] < 0 }
  .reject {|t| t["category_id"] == "2106381" || t["category"] == "Benefits" }

Answer 2

现在还不清楚你到底想要实现什么，但根据我的理解，你想要：

( 1)包括所有负amount的事务2)排除具有指定category_id 3的所有事务)排除具有指定category的所有事务

要做到这一点，可以执行以下操作：

@transactions.find_all do |t|
  t['amount'] < 0 &&
  t['category_id'] != '2106381' &&
  t['category'] != ["BENEFITS"]
end

Answer 3

下面的解决方案为"amount"提供了三种不同的场景，并将"categories"格式化为小写。

require 'pp' # require pretty_print

@transactions = [
  {"amount"=>-20, "name"=>"DEPOSIT", "category"=> ["BENEFITS"],"category_id"=>"21007000"},
  {"amount"=>-0.8, "name"=>"XFER", "category"=>["Transfer", "Credit"], "category_id"=>"2106381"},
  {"amount"=>-20, "name"=>"DEPOSIT", "category"=>["Transfer", "Deposit"], "category_id"=>"21007000"},
  {"amount"=>-1, "name"=>"XFER", "category"=>["Transfer", "Credit"], "category_id"=>"21005000"},
  {"amount"=>300.80, "name"=>"XFER", "category"=>"Food", "category_id"=>"2106381"}
]

# Enumerable#find_all
# see: http://ruby-doc.org/core-2.2.3/Enumerable.html#method-i-find_all
items = @transactions.find_all do |t|

  # 1) amount is less than zero
  t.fetch('amount') < 0 && 

  # 2) amount is less than zero or zero
  #t.fetch('amount') <= 0 && 

  # 3) Ruby 2.3 use core method: Numeric#negative?
  # see: http://ruby-doc.org/core-2.3.0/Numeric.html#method-i-negative-3F
  # see: https://github.com/ruby/ruby/blob/3a48e12/numeric.c#L4196-L4197
  # via: http://stackoverflow.com/a/34146626
  #t.fetch('amount').negative? &&

  t.fetch('category_id') != '2106381' &&

  # category is array so map and downcase before Array#include?
  # see: http://ruby-doc.org/core-2.2.3/Array.html#method-i-map
  # see: http://ruby-doc.org/core-2.2.3/Array.html#method-i-include-3F
  !(t.fetch('category').map {|c| c.downcase}.include?("benefits"))
end

pp items
# [{"amount"=>-20,
#  "name"=>"DEPOSIT",
#  "category"=>["Transfer", "Deposit"],
#  "category_id"=>"21007000"},
# {"amount"=>-1,
#  "name"=>"XFER",
#  "category"=>["Transfer", "Credit"],
#  "category_id"=>"21005000"}]