填充表格数据的打印输出

MarkusQ.. 18

试试String#rjust(width):

"hello".rjust(20)           #=> "               hello"

Chris Doyle.. 18

我写了一个宝石来做到这一点:http://tableprintgem.com

试试String#rjust(width):

"hello".rjust(20)           #=> "               hello"

我写了一个宝石来做到这一点:http://tableprintgem.com

没有人提到"最酷"/最紧凑的方式 - 使用%运营商 - 例如:"%10s %10s" % [1, 2].这是一些代码:

xs = [
  ["This code", "is", "indeed"],
  ["very", "compact", "and"],
  ["I hope you will", "find", "it helpful!"],
]
m = xs.map { |_| _.length }
xs.each { |_| _.each_with_index { |e, i| s = e.size; m[i] = s if s > m[i] } }
xs.each { |x| puts m.map { |_| "%#{_}s" }.join(" " * 5) % x }

得到:

      This code          is          indeed
           very     compact             and
I hope you will        find     it helpful!

这里的代码更具可读性:

max_lengths = xs.map { |_| _.length }
xs.each do |x|
  x.each_with_index do |e, i|
    s = e.size
    max_lengths[i] = s if s > max_lengths[i]
  end
end
xs.each do |x|
  format = max_lengths.map { |_| "%#{_}s" }.join(" " * 5)
  puts format % x
end

这是一个相当完整的例子,假设如下

您的产品列表包含在名为veg.txt的文件中

您的数据按每条记录排列三行,并且字段在连续的行上

我对rails来说有点像菜鸟,所以毫无疑问会有更好,更优雅的方式来做到这一点

#!/usr/bin/ruby

class Vegetable

  @@max_name ||= 0  
  @@max_variety ||= 0  
  @@max_container ||= 0  

  attr_reader :name, :variety, :container

  def initialize(name, variety, container)
    @name = name
    @variety = variety
    @container = container  

    @@max_name = set_max(@name.length, @@max_name)  
    @@max_variety = set_max(@variety.length, @@max_variety)  
    @@max_container = set_max(@container.length, @@max_container)
  end

  def set_max(current, max)
    current > max ? current : max
  end

  def self.max_name  
    @@max_name  
  end  

  def self.max_variety  
    @@max_variety  
  end  

  def self.max_container()  
    @@max_container  
  end  

end

    products = []


    File.open("veg.txt") do | file|

      while name = file.gets
        name = name.strip
        variety = file.gets.to_s.strip
        container = file.gets.to_s.strip
        veg = Vegetable.new(name, variety, container)
        products << veg
      end
    end

    format="%#{Vegetable.max_name}s\t%#{Vegetable.max_variety}s\t%#{Vegetable.max_container}s\n"
    printf(format, "Name", "Variety", "Container")
    printf(format, "----", "-------", "---------")
    products.each do |p|
        printf(format, p.name, p.variety, p.container)
    end

以下示例文件

Artichoke
Green Globe, Imperial Star, Violetto
24" deep
Beans, Lima
Bush Baby, Bush Lima, Fordhook, Fordhook 242
12" wide x 8-10" deep
Potatoes
King Edward, Desiree, Jersey Royal
36" wide x 8-10" deep

产生以下输出

       Name                                      Variety                Container
       ----                                      -------                ---------
  Artichoke         Green Globe, Imperial Star, Violetto                 24" deep
Beans, Lima Bush Baby, Bush Lima, Fordhook, Fordhook 242    12" wide x 8-10" deep
   Potatoes           King Edward, Desiree, Jersey Royal    36" wide x 8-10" deep