ruby 字符串中选定字符替换的所有可能组合

Question

我想知道是否有一种简单的方法可以在 ruby​​ 中以简单的方式完成所选字符替换的每个组合。

一个例子：

    string = "this is a test"
    subs = ['a'=>'@','i'=>'!','s'=>'$']
    subs.combination.each { |c|
        string.gsub c
    }

会产生

    "this is @ test"
    "th!s !s a test"
    "thi$ i$ a te$t"
    "th!s !s @ test"
    "thi$ i$ @ te$t"
    "th!$ !$ a te$t"
    "th!$ !$ @ te$t"

感谢您的帮助！

Answer 1

我会这样做：

string = "this is a test"
subs = {'a'=>'@','i'=>'!','s'=>'$'}

keys = subs.keys
combinations = 1.upto(subs.size).flat_map { |i| keys.combination(i).to_a }

combinations.each do |ary|
  new_string = string.dup
  ary.each { |c| new_string.gsub!(c,subs) }
  puts new_string
end

输出

this is @ test
th!s !s a test
thi$ i$ a te$t
th!s !s @ test
thi$ i$ @ te$t
th!$ !$ a te$t
th!$ !$ @ te$t

Answer 2

string = "this is a test"
subs = ['a'=>'@','i'=>'!','s'=>'$']

subs = subs.first.map(&:to_a)
1.upto(subs.length).each do |n|
  subs.combination(n).each do |a|
    p a.each_with_object(string.dup){|pair, s| s.gsub!(*pair)}
  end
end

Answer 3

我会使用String#gsub(pattern, hash) 执行以下操作：

string = "this is a test"
subs = {'a'=>'@','i'=>'!','s'=>'$'} # copied from @ArupRakshit
keys = subs.keys

及核心代码：

1.upto(keys.length).flat_map { |i| 
  keys.combination(i).flat_map { |c| string.gsub(/[#{c.join}]/, subs) } 
}

输出：

=> ["this is @ test",
 "th!s !s a test",
 "thi$ i$ a te$t",
 "th!s !s @ test",
 "thi$ i$ @ te$t",
 "th!$ !$ a te$t",
 "th!$ !$ @ te$t"]

Answer 4

另一种方式：

string = "this is a test"
subs   = [{"a"=>"@"}, {"i"=>"!"}, {"s"=>"$"}]

subs.repeated_combination(subs.size)
    .map {|e| string.gsub(/./) {|c| (g = e.find {|h| h.key?(c)}) ? g[c] : c}}
    .uniq
  #=> ["this is @ test", "th!s !s @ test", "thi$ i$ @ te$t", "th!$ !$ @ te$t",
  #    "th!s !s a test", "th!$ !$ a te$t", thi$ i$ a te$t"]

解释：

a = subs.repeated_combination(subs.size)
  # Enumerator...
  a.to_a 
  # [[{"a"=>"@"},{"a"=>"@"},{"a"=>"@"}], [{"a"=>"@"},{"a"=>"@"},{"i"=>"!"}],
  #  [{"a"=>"@"},{"a"=>"@"},{"s"=>"$"}], [{"a"=>"@"},{"i"=>"!"},{"i"=>"!"}],
  #  [{"a"=>"@"},{"i"=>"!"},{"s"=>"$"}], [{"a"=>"@"},{"s"=>"$"},{"s"=>"$"}],
  #  [{"i"=>"!"},{"i"=>"!"},{"i"=>"!"}], [{"i"=>"!"},{"i"=>"!"},{"s"=>"$"}],
  #  [{"i"=>"!"},{"s"=>"$"},{"s"=>"$"}], [{"s"=>"$"},{"s"=>"$"},{"s"=>"$"}]]

b = a.map {|e| string.gsub(/./) {|c| (g = e.find {|h| h.key?(c)}) ? g[c] : c}}
  #=> ["this is @ test", "th!s !s @ test", "thi$ i$ @ te$t", "th!s !s @ test",
  #    "th!$ !$ @ te$t", "thi$ i$ @ te$t", "th!s !s a test", "th!$ !$ a te$t",
  #    "th!$ !$ a te$t", "thi$ i$ a te$t"]

要查看b 是如何计算的，请考虑a 中传递给块的第二个元素：

    e = [{"a"=>"@"},{"a"=>"@"},{"i"=>"!"}]

由于正则表达式，/./、gsub 将string 中的每个字符c 传递给块

    {|c| (g = e.find {|h| h.key?(c)}) ? g[c] : c}

对e 进行搜索以确定三个散列中的任何一个是否以c 作为键。如果找到一个，即g，则将字符c替换为g[c]；否则，字符保持不变。

注意e 的前两个元素是相同的。将第一行改为：

    subs.repeated_combination(subs.size).map(&:uniq)

但效率不是这种方法的优点之一。

回到主计算，最后一步是：

b.uniq
  #=> ["this is @ test", "th!s !s @ test", "thi$ i$ @ te$t", "th!$ !$ @ te$t",
  #    "th!s !s a test", "th!$ !$ a te$t", "thi$ i$ a te$t"]

Answer 5

单线功能解决方案

string = "this is a test"
subs = {'a'=>'@','i'=>'!','s'=>'$'}

(1..subs.size).flat_map { |n| subs.keys.combination(n).to_a }.map { |c| string.gsub(/[#{c.join}]/, subs) }
# => ["this is @ test", "th!s !s a test", "thi$ i$ a te$t", "th!s !s @ test", "thi$ i$ @ te$t", "th!$ !$ a te$t", "th!$ !$ @ te$t"]