如何将数组附加为哈希值

Posted 2021-05-05

我有一个我正在尝试处理的CSV文件。我想在文件中创建一些字段的哈希值，但代码只输出键的最后一条记录而不是三条记录。

Season,Rk,Tm,G,PF,Yds,Ply,Y/P,TO,FL,1stD,Cmp,Att,Yds,TD,Int,NY/A,1stD,Att,Yds,TD,Y/A,1stD,Pen,Yds,1stPy,Sc%,TO%,EXP
2015,1,Carolina Panthers,16,500,5871,1060,5.5,19,9,357,300,501,3589,35,10,6.7,197,526,2282,19,4.3,136,103,887,24,42.9,9.6,125.65
2015,2,Arizona Cardinals,16,489,6533,1041,6.3,24,11,373,353,562,4616,35,13,7.8,237,452,1917,16,4.2,92,94,758,44,42.5,11.8,168.18
2014,19,Carolina Panthers,16,339,5547,1060,5.2,23,11,347,327,545,3511,23,12,6,199,473,2036,10,4.3,117,83,756,31,34.8,11.8,29.83
2014,24,Arizona Cardinals,16,310,5116,993,5.2,17,5,302,320,568,3808,21,12,6.4,191,397,1308,6,3.3,67,91,707,44,30.9,9.4,-15.68
2013,17,Arizona Cardinals,16,379,5542,1037,5.3,31,9,329,363,574,4002,24,22,6.5,205,422,1540,12,3.6,84,96,744,40,33,15.5,-11.6
2013,18,Carolina Panthers,16,366,5069,999,5.1,19,6,319,292,473,3043,24,13,5.9,169,483,2026,14,4.2,122,80,671,28,36.5,9.4,70.12

这是我创建哈希的代码：

require 'csv'

teams = {}

CSV.foreach("/home/rl/data/test-file.csv", :headers => true, :header_converters => :symbol, :converters => :all) do |row|
        teams[row.fields[2]] = Hash[row.headers[3..5].zip(row.fields[3..5])]
end

puts teams

这是我的输出。我期待每个键有三个记录，关键是团队：

{"Carolina Panthers"=>{:g=>16, :pf=>366, :yds=>5069}, "Arizona Cardinals"=>{:g=>16, :pf=>379, :yds=>5542}}

答案

改变了团队......

teams = Hash.new{|val,key| val[key] = []}

现在按预期输出......

{"Carolina Panthers"=>[{:g=>16, :pf=>500, :yds=>5871}, {:g=>16, :pf=>339, :yds=>5547}, {:g=>16, :pf=>366, :yds=>5069}], "Arizona Cardinals"=>[{:g=>16, :pf=>489, :yds=>6533}, {:g=>16, :pf=>310, :yds=>5116}, {:g=>16, :pf=>379, :yds=>5542}]}

另一答案

您获得每个组的最后一条记录，因为您实际上每次都重写它而不是将其添加到集合中。为了避免它使用：

# Push records to each collection by group instead of rewriting it
( teams[row.fields[2]]||=[] ) << Hash[row.headers[3..5].zip(row.fields[3..5])]

另一答案

这是我写的方式：

require 'awesome_print'
require 'csv'

teams = Hash.new { |h, k| h[k] = [] }
fields = [:g, :pf, :yds]
CSV.foreach( 
  'test.csv',
  headers: true,
  header_converters: :symbol,
  converters: :all
) do |row|
  teams[row[:tm]] << fields.zip(row.values_at(*fields)).to_h
end

ap teams

在运行和读取CSV后，输出：

{
  "Carolina Panthers" => [
    [0] {
      :g   => 16,
      :pf  => 500,
      :yds => 5871
    },
    [1] {
      :g   => 16,
      :pf  => 339,
      :yds => 5547
    },
    [2] {
      :g   => 16,
      :pf  => 366,
      :yds => 5069
    }
  ],
  "Arizona Cardinals" => [
    [0] {
      :g   => 16,
      :pf  => 489,
      :yds => 6533
    },
    [1] {
      :g   => 16,
      :pf  => 310,
      :yds => 5116
    },
    [2] {
      :g   => 16,
      :pf  => 379,
      :yds => 5542
    }
  ]
}

你告诉CSV使用符号作为标题名称，这使你很容易访问返回的row中的值，所以这样做。这样阅读和维护要容易得多。

Hash.new { |h,k| h[k] = [] }是为新创建的键/值对自动创建数组值的Ruby方法。

最后，Awesome Print，AKA 'ap'，是一个可视化数据的好工具。

另一答案

每次为哈希中的现有键分配一些值时，都会更新此键的值。

my_hash = {a: "me a", b: "me b"}  
my_hash[:a] = "another a"  
my_hash #=> {:a=>"another a", :b=>"me be"}

如您所见，在您的示例中，两个键的值"Carolina Panthers"和"Arizona Cardinals"被分配给列表中的最后一个值。