更改所有包含特定字符串的數組元素

Question

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

我想從數組中選擇包含單詞'good'的元素並將該字符串設置爲新變量。我怎麼能這樣做？

Answer 1

這幾乎就像你輸入你的標題：

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

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

Answer 2

還有這個特殊的方法：

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

有了你可以做一個#grep很多，因爲它需要一個正則表達式...

Answer 3

既然沒有答案到目前爲止，指導您如何更新數組新值的字符串，這裏有一些選擇：

# 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，上述所有會改變一個字符串的所有實例。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... 

如果你不希望這個副作用，如果你想更換一個不同字符串數組中的字符串，而不是變化字符串本身，那麼你需要找到該項目，並更新索引：

# 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" } 

最後，最簡單和最快的大多是無擺弄指數：

# 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!聽起來是一個不錯的選擇。

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