我正确地扩展这个内置的ruby类吗？

问题描述

在我的rails应用程序在lib / matrix.rb我已经输入以下代码来扩展内置的Matrix类：

 模块矩阵
 
需要'matrix'
 
 class Matrix 
 def symmetric？ 
如果不是方形，返回false？ 
（0 ... row_size）.each do | i | 
（0 .. i）.each do | j | 
 return false if self [i，j]！= self [j，i] 
 end 
 end 
 true 
 end 
 
 cholesky_factor 
 raise ArgumentError，必须提供对称矩阵，除非对称？ 
 l = Array.new（row_size）{Array.new（row_size，0）} 
（0 ... row_size）.each do | k | 
（0 ... row_size）.each do | i | 
 if i == k 
 sum =（0 .. k-1）.inject（0.0）{| sum，j | sum + l [k] [j] ** 2} 
 val = Math.sqrt（self [k，k]  -  sum）
l [k] [k] = val 
 elsif i > k 
 sum =（0 .. k-1）.inject（0.0）{| sum，j | sum + l [i] [j] * l [k] [j]} 
 val =（self [k，i]  -  sum）/ l [k] k] = val 
 end 
 end 
 end 
 Matrix [* l] 
 end 
 end 
 end 
  

这是在rails应用程序中向现有类添加方法的正确方法吗？

编辑1：提供额外资讯

如果在视图页面中输入以下测试代码，只有在我删除了lib / matrix.rb文件：

 <％require'matrix'％& 
 
<％
 
m = Matrix [
 [0,0]，
 [1,1] 
] 
 
％> 
 
<％= m.column（0）％> 
  

否则会出现错误：

 未定义方法`[]'for Matrix：模块
  

当我尝试扩展类时，我消除了内置的Matrix类的默认方法。有没有办法解决这个错误？

解决方案

这里不需要'matrix'。谁使用你的代码（rails应用程序在你的情况下），应该使用require'matrix'

In my rails app in lib/matrix.rb I have entered the following code to extend the inbuilt Matrix class:

module Matrix

  require 'matrix'

  class Matrix
    def symmetric?
      return false if not square?
      (0 ... row_size).each do |i|
        (0 .. i).each do |j|
          return false if self[i,j] != self[j,i]
        end
      end
      true
    end

    def cholesky_factor
      raise ArgumentError, "must provide symmetric matrix" unless symmetric?
      l = Array.new(row_size) {Array.new(row_size, 0)}
      (0 ... row_size).each do |k|
        (0 ... row_size).each do |i|
          if i == k
            sum = (0 .. k-1).inject(0.0) {|sum, j| sum + l[k][j] ** 2}
            val = Math.sqrt(self[k,k] - sum)
            l[k][k] = val
          elsif i > k
            sum = (0 .. k-1).inject(0.0) {|sum, j| sum + l[i][j] * l[k][j]}
            val = (self[k,i] - sum) / l[k][k]
            l[i][k] = val
          end
        end
      end
      Matrix[*l]
    end
  end
end

Is this the correct way to add methods to an existing class within the rails app? Should I have the require matrix line there?

EDIT 1: Additional info provided

I have now removed the require 'matrix' line.

If I type the following test code in a view page, it only works if I delete my lib/matrix.rb file:

<% require 'matrix' %>

<%

m = Matrix[
   [0,0],
   [1,1]
   ]

%>

<%= m.column(0) %>

Otherwise it gives the error:

undefined method `[]' for Matrix:Module

It appears that I am eliminating the default methods of the built in Matrix class when I try to extend the class. Is there a way around this error?

解决方案

no you should not have to require 'matrix' here. Whoever uses your code(rails app in your case), should use require 'matrix'

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