使用gsub - Ruby在字符之间插入空格

Question

假设我有一个字符串"我在24个国家的54个房子里养了36只狗"。是否有可能仅使用gsub在每个数字之间添加"，以便字符串变成"我在24个国家的54个房子里有36只狗"?

gsub(/(d)(d)/, "#{$1} #{$2}")不能工作，因为它将每个数字替换为一个空格，gsub(/dd/, "d d")也不能工作，它将每个数字替换为d。

Answer 1

s = "I have 3651 dogs in 24 countries"

使用String#gsub:

的四种方法

使用正向向前看并捕获组

r = /
    (d)   # match a digit in capture group 1
    (?=d) # match a digit in a positive lookahead
    /x     # extended mode
s.gsub(r, '1 ')
  #=> "I have 3 6 5 1 dogs in 2 4 countries"

正面的look - behind也可以用:

s.gsub(/(?<=d)(d)/, ' 1')

使用block

s.gsub(/d+/) { |s| s.chars.join(' ') }
  #=> "I have 3 6 5 1 dogs in 2 4 countries"

使用正向向前看和块

s.gsub(/d(?=d)/) { |s| s + ' ' }
  #=> "I have 3 6 5 1 dogs in 2 4 countries"

使用散列

h = '0'.upto('9').each_with_object({}) { |s,h| h[s] = s + ' ' }
  #=> {"0"=>"0 ", "1"=>"1 ", "2"=>"2 ", "3"=>"3 ", "4"=>"4 ",
  #    "5"=>"5 ", "6"=>"6 ", "7"=>"7 ", "8"=>"8 ", "9"=>"9 "} 
s.gsub(/d(?=d)/, h)
  #=> "I have 3 6 5 1 dogs in 2 4 countries" 

Answer 2

另一种方法是使用前向和后向查找数字之间的位置，然后将其替换为空格。

[1] pry(main)> s = "I have 36 dogs in 54 of my houses in 24 countries"
=> "I have 36 dogs in 54 of my houses in 24 countries"
[2] pry(main)> s.gsub(/(?<=d)(?=d)/, ' ')
=> "I have 3 6 dogs in 5 4 of my houses in 2 4 countries"

Answer 3

为了引用匹配项，您应该使用n，其中n是匹配项，而不是$1。

s = "I have 36 dogs in 54 of my houses in 24 countries"
s.gsub(/(d)(d)/, '1 2') 
# => "I have 3 6 dogs in 5 4 of my houses in 2 4 countries"