ruby 如何将字符串数组转换为符号数组？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/16502866/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to convert a array of strings to an array of symbols?
提问by Gracko
I want to convert the elements of the string array below to symbols, and output them
我想将下面的字符串数组的元素转换为符号，并输出它们
strings = ["HTML", "CSS", "JavaScript", "Python", "Ruby"]
look at what I'm doing:
看看我在做什么：
strings.each { |x| puts x.to_sym }
No success. What am I doing wrong?
没有成功。我究竟做错了什么？
回答by icktoofay
Use maprather than each:
使用map而不是each：
>> strings.map { |x| x.to_sym }
=> [:HTML, :CSS, :JavaScript, :Python, :Ruby]
For Ruby 1.8.7 and later or with ActiveSupport included, you can use this syntax:
对于 Ruby 1.8.7 及更高版本或包含 ActiveSupport，您可以使用以下语法：
>> strings.map &:to_sym
=> [:HTML, :CSS, :JavaScript, :Python, :Ruby]
The reason your eachmethod appears to not work is that calling putswith a symbol outputs the string representation of the symbol (that is, without the :). Additionally, you're just looping through and outputting things; you're not actually constructing a new array.
您的each方法似乎不起作用的原因是puts使用符号调用会输出符号的字符串表示形式（即，没有:）。此外，您只是循环并输出内容；你实际上并不是在构建一个新数组。
回答by cb24
Clean one-liner:
清洁单层：
%w(HTML CSS JavaScript Python Ruby).map(&:to_sym)
&tells argument should be treated as a block, i.e. build up array and apply to_symto each element.
&告诉参数应该被视为一个块，即构建数组并应用于to_sym每个元素。
回答by DaniG2k
I'd do something like
我会做类似的事情
strings.map! &:to_sym
回答by knut
icktoofay already gave the correct answer.
On additional remark: With
补充说明：与
strings.map { |x| x.to_sym }
you get a new array, the original array is unchanged.
你得到一个新数组，原始数组不变。
To use it, you can assign it to another variable:
要使用它，您可以将它分配给另一个变量：
string2 = strings.map { |x| x.to_sym }
If you want to modify string, you can use map!:
如果要修改字符串，可以使用map!：
strings.map! { |x| x.to_sym }
回答by Teddy
@icktoofay has the correct answer, but just to help you better understand the eachmethod, here is how you can do the same thing using each:
@icktoofay 有正确的答案，但只是为了帮助您更好地理解该each方法，以下是您可以使用each以下方法执行相同操作的方法：
strings = ["HTML", "CSS", "JavaScript", "Python", "Ruby"]
symbols = [] # an empty array to hold our symbols
strings.each { |s| symbols << s.to_sym }
回答by Lomefin
@cb24's answer is generally the most appropiate, I wanted to compare that solution with another one
@cb24 的答案通常是最合适的，我想将该解决方案与另一个解决方案进行比较
strings.collect {|x| x.to_sym }
I did some benchmarks and @cb24's answer works best in most cases, when there are some more elements in the array, but if it happens to be a very tiny array, the collect method works a little faster.
我做了一些基准测试，@cb24 的答案在大多数情况下效果最好，当数组中有更多元素时，但如果它恰好是一个非常小的数组，collect 方法的工作速度会快一些。
I publish here the code and the results, this is my real first benchmark so if I got something wrong some feedback would be appreciated. I did it on both String -> Symbol and Symbol -> String
我在这里发布了代码和结果，这是我真正的第一个基准测试，所以如果我有什么问题，一些反馈将不胜感激。我在 String -> Symbol 和 Symbol -> String 上都做了
n = 1000000
a = [:a,:b,:c,:d,:e,:f,:g,:h,:i].freeze #A "long" array of symbols
Benchmark.bm do |x|
x.report { n.times { a.map(&:to_s)} }
x.report { n.times { a.collect{|x| x.to_s}} }
end
user system total real
2.040000 0.010000 2.050000 ( 2.056784)
2.100000 0.010000 2.110000 ( 2.118546)
b = [:a, :b].freeze #Small array
Benchmark.bm do |x|
x.report { n.times { b.map(&:to_s)} }
x.report { n.times { b.collect{|x| x.to_s}} }
end
user system total real
0.610000 0.000000 0.610000 ( 0.622231)
0.530000 0.010000 0.540000 ( 0.536087)
w = %w(a b).freeze #Again, a small array, now of Strings
Benchmark.bm do |x|
x.report { n.times { w.map(&:to_sym)} }
x.report { n.times { w.collect{|x| x.to_sym}} }
end
user system total real
0.510000 0.000000 0.510000 ( 0.519337)
0.440000 0.010000 0.450000 ( 0.447990)
y = %w(a b c d e f g h i j k l m n o p q).freeze #And a pretty long one
Benchmark.bm do |x|
x.report { n.times { y.map(&:to_sym)} }
x.report { n.times { y.collect{|x| x.to_sym}} }
end
user system total real
2.870000 0.030000 2.900000 ( 2.928830)
3.240000 0.030000 3.270000 ( 3.371295)
The inflection points I didn't calculate but it is quite interesting, I read somewhere that some improvements where made with short arrays, since most of them are just a couple of elements long.
我没有计算拐点，但它很有趣，我在某处读到了一些使用短数组进行的改进，因为它们中的大多数只是几个元素的长度。
回答by Frank Koehl
If you want to go the gem route, finishing_moveshas an Array#to_sym_strictmethod that does exactly what you're looking for:
如果你想走 gem 路线，finishing_moves有一个Array#to_sym_strict方法可以满足你的需求：
strings = ["HTML", "CSS", "JavaScript", "Python", "Ruby"]
strings.to_sym_strict
# => [:HTML, :CSS, :JavaScript, :Python, :Ruby]
There's also a #to_sym_looseto handle arrays of mixed type:
还有一个#to_sym_loose用于处理混合类型的数组：
strings = ["HTML", "CSS", "JavaScript", "Python", "Ruby", 1, /a regex/, {a: :hash}]
strings.to_sym_loose
# => [:HTML, :CSS, :JavaScript, :Python, :Ruby, 1, /a regex/, {a: :hash}]
# no exceptions thrown
回答by Harsha
Or can be done as follows:
或者可以按如下方式完成：
strings.each do |s|
symbols.push(s.to_sym)
