Question

我遇到了一个问题-解决了一个我有.yml文件的任务，

time:
  -
    begin: :washington
    end: :briston
    min: 6
    price: 3
  -
    begin: :briston
    end: :dallas
    min: 4
    price: 2
  -
    begin: :dallas
    end: :tokyo
    min: 3.5
    price: 3
  -
    begin: :tokyo
    end: :chicago
    min: 3.5
    price: 3

和一列Train，我想在其中循环浏览.yml文件并提取必要的信息，并使用这些值（起点，终点，价格和持续时间）进行操作。

class Train 
  require 'yaml'

  def initialize(time, line)
    @time = YAML.load_file(time)
    @line = YAML.load_file(line)
  end

  def calc(begin, end)
    @time.select do |key, value|
      puts key, value
    end
  end
end

在'calc'方法中，我定义了'select'方法来检索键和值，但它只是打印所有散列，如下所示：

time
{"begin"=>:washington, "end"=>:briston, "min"=>6, "price"=>3}
{"begin"=>:briston, "end"=>:dallas, "min"=>4, "price"=>2}
{"begin"=>:dallas, "end"=>:tokyo, "min"=>3.5, "price"=>3}

如何遍历此哈希以提取必要的数据？预先感谢！

Answer 1

如果我明白这一点，请参阅变量@time，查看我的评论：

@time = {"time"=>[{"begin"=>:washington, "end"=>:briston, "min"=>6, "price"=>3}, {"begin"=>:briston, "end"=>:dallas, "min"=>4, "price"=>2}, {"begin"=>:dallas, "end"=>:tokyo, "min"=>3.5, "price"=>3}, {"begin"=>:tokyo, "end"=>:chicago, "min"=>3.5, "price"=>3}]}

一种可重构的链接方式：

ary = @time['time']
start = :washington
stop = :tokyo
res = []
loop do
  tmp = ary.find { |h| h['begin'] == start }
  break unless tmp
  res << tmp
  start = tmp['end']
  break if start == stop
end

然后您有res：

#=> [{"begin"=>:washington, "end"=>:briston, "min"=>6, "price"=>3}, {"begin"=>:briston, "end"=>:dallas, "min"=>4, "price"=>2}, {"begin"=>:dallas, "end"=>:tokyo, "min"=>3.5, "price"=>3}]

例如要获取min的总和：

res.sum { |h| h['min'] } #=> 13.5

如何遍历嵌套数组/哈希并从中检索数据

1 个答案: