logo标签列表

在Ruby中，针对哈希数组的sort_by方法未能产生预期结果

arraysrubyhashruby-2.3
3

我有以下数组

arr = [
    { nbr: "979276030", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "03/23/2016 12:00 AM", name: "Brad Pacocha" },
    { nbr: "910482832", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "08/23/2015 12:00 AM", name: "Aracely Bogan" },
    { nbr: "819205275", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "09/02/2015 12:00 AM", name: "Kelli Moore" },
    { nbr: "755667162", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "10/16/2015 12:00 AM", name: "Trace Auer" },
    { nbr: "561189198", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "01/11/2016 12:00 AM", name: "Geoffrey Will" },
    { nbr: "429905984", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "04/25/2016 12:00 AM", name: "Martine Berge" },
    { nbr: "421919042", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "02/26/2016 12:00 AM", name: "Jewel Bailey" },
    { nbr: "274874145", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "04/19/2016 12:00 AM", name: "Wendell Tremblay" },
    { nbr: "254548319", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "01/16/2016 12:00 AM", name: "Dewitt Ritchie" },
    { nbr: "250154069", des: "CONF NO COST 30 Refi Plus <= 105 SM SRVR", status: "2C", milestone: "Processing", dt_time: "10/12/2015 12:00 AM", name: "Lisette Wehner" }
]

sort_arr = arr.sort_by { |h| h[:des] }

puts arr
puts '*'*100
puts sort_arr

我希望排序后的结果应该与我的源数组相同，因为所有哈希的键都具有相同的值。

但我得到了以下结果：

{:nbr=>"250154069", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"10/12/2015 12:00 AM", :name=>"Lisette Wehner"}
{:nbr=>"910482832", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"08/23/2015 12:00 AM", :name=>"Aracely Bogan"}
{:nbr=>"819205275", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"09/02/2015 12:00 AM", :name=>"Kelli Moore"}
{:nbr=>"755667162", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"10/16/2015 12:00 AM", :name=>"Trace Auer"}
{:nbr=>"561189198", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"01/11/2016 12:00 AM", :name=>"Geoffrey Will"}
{:nbr=>"429905984", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"04/25/2016 12:00 AM", :name=>"Martine Berge"}
{:nbr=>"421919042", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"02/26/2016 12:00 AM", :name=>"Jewel Bailey"}
{:nbr=>"274874145", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"04/19/2016 12:00 AM", :name=>"Wendell Tremblay"}
{:nbr=>"254548319", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"01/16/2016 12:00 AM", :name=>"Dewitt Ritchie"}
{:nbr=>"979276030", :des=>"CONF NO COST 30 Refi Plus <= 105 SM SRVR", :status=>"2C", :milestone=>"Processing", :dt_time=>"03/23/2016 12:00 AM", :name=>"Brad Pacocha"}

第一个和最后一个哈希值被交换了。

这是一个有效的结果吗？为什么会出现这种行为？

1个回答
4

Ruby的Array#sort_by使用了快速排序算法的高效实现。

快速排序是一种比较排序，意味着它可以对任何定义了“小于”关系（形式上，一个全序关系）的类型进行排序。 在高效的实现中，它不是稳定排序，这意味着相等的排序项的相对顺序不会被保留。 - 维基百科快速排序文章

1
如果你按某种键和数组中的原始索引作为次要考虑因素进行排序，它就可以变得稳定。 - tadman
网页内容由stack overflow 提供, 点击上面的
可以查看英文原文，
原文链接