更改所有包含特定字符串的数组元素

Question

array = ["Spam is bad", "Ham is good"] 

我想从数组中选择包含单词'good'的元素并将该字符串设置为新变量。我怎么能这样做？

Answer 1

这几乎就像你输入你的标题：

array.select {|s| s.include? "good"} 

这里的DOC：http://www.ruby-doc.org/core-1.9.3/Array.html#method-i-select

Answer 2

还有这个特殊的方法：

array.grep(/good/) # => ["Ham is good"] 

有了你可以做一个#grep很多，因为它需要一个正则表达式...

Answer 3

既然没有答案到目前为止，指导您如何更新数组新值的字符串，这里有一些选择：

# Find every string matching a criteria and change them 
array.select{ |s| s.include? "good" }.each{ |s| s.replace("bad") } 

# Find every string matching a pattern and change them 
array.grep.replace("bad").each{ |s| s.replace("bad") } 

# Find the first string matching a criteria and change it 
array.find{ |s| s =~ /good/ }.replace("bad") 

然而，上述所有会改变一个字符串的所有实例。例如：

jon = Person.new "Johnny B. Goode" 
array = [ jon.name, "cat" ] 
array.find{ |s| s =~ /good/i }.replace("bad") 

p array #=> "bad" 
p jon #=> #<Person name="bad"> Uh oh... 

如果你不希望这个副作用，如果你想更换一个不同字符串数组中的字符串，而不是变化字符串本身，那么你需要找到该项目，并更新索引：

# Find the _first_ index matching some criteria and change it 
array[ array.index{ |s| s =~ /good/ } ] = "bad" 

# Update _every_ item in the array matching some criteria  
array[i] = "bad" while i = array.index{ |s| s =~ /good/i } 

# Another way to do the above 
# Possibly more efficient for very large arrays any many items 
indices = array.map.with_index{ |s,i| s =~ /good/ ? i : nil }.compact 
indices.each{ |i| array[i] = "bad" } 

最后，最简单和最快的大多是无摆弄指数：

# Create a new array with the new values 
new_array = array.map do |s| 
    if s =~ /good/i # matches "Good" or "good" in the string 
    "bad" 
    else 
    s 
    end 
end 

# Same thing, but shorter syntax 
new_array = array.map{ |s| s =~ /good/i ? "bad" : s } 

# Or, change the array in place to the new values 
new_array = array.map!{ |s| s =~ /good/i ? "bad" : s } 

Answer 4

map!听起来是一个不错的选择。

x = ['i', 'am', 'good'] 
def change_string_to_your_liking s 
    # or whatever it is you plan to do with s 
    s.gsub('good', 'excellente!') 
end 
x.map! {|i| i =~ /good/ ? change_string_to_your_liking(i) : i} 
puts x.inspect