blocks|key|979992|text|一种不会给原始文件带来副作用的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|979993|h+=+{:a+=>+'a',+:b+=>+'b'}
h2+=+Hash[h.map+{%7Ck,v%7C+[k,+'%25'+%2B+v+%2B+'%25']}]|code-block|syntax|javascript|979994|Hash#map也可能是一个有趣的读物，因为它解释了为什么Hash.map不返回散列(这就是为什么[key,value]对的结果数组被转换为新的散列)，并为相同的通用模式提供了替代方法。|offset|length|style|CODE|979995|祝你编码愉快。|979996|免责声明:我不确定Ruby2.x中的Hash.map语义是否发生了变化|979997|entityMap|0|LINK|mutability|MUTABLE|url|http://www.ruby-forum.com/topic/185611^0|0|0|T|8|1D|B|0|8|0|0|0|I|8|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@$I|11|J|12|K|L]|$I|13|J|14|K|L]]|9|@$I|15|J|16|1|17]]|A|$]]|$1|M|3|N|5|6|7|18|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|19|8|@$I|1A|J|1B|K|L]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

One method that doesn't introduce side-effects to the original:

<pre><code>h = {:a =&gt; 'a', :b =&gt; 'b'}
h2 = Hash[h.map {|k,v| [k, '%' + v + '%']}]
</code></pre>

<a href="http://www.ruby-forum.com/topic/185611" rel="noreferrer">Hash#map</a> may also be an interesting read as it explains why the <code>Hash.map</code> doesn't return a Hash (which is why the resultant Array of <code>[key,value]</code> pairs is converted into a new Hash) and provides alternative approaches to the same general pattern.

Happy coding.

[Disclaimer: I am not sure if <code>Hash.map</code> semantics change in Ruby 2.x]

blocks|key|764698|text|my_hash.each+do+%7Ckey,+value%7C
++my_hash[key]+=+"%25#{value}%25"
end|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|764699|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>my_hash.each do |key, value|
 my_hash[key] = "%#{value}%"
end
</code></pre>

blocks|key|764756|text|如果您希望实际字符串本身在适当的位置发生变化(可能会影响对相同字符串对象的其他引用)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|764757|#+Two+ways+to+achieve+the+same+result+(any+Ruby+version)
my_hash.each{+%7C_,str%7C+str.gsub!+/%5E%7C$/,+'%25'+}
my_hash.each{+%7C_,str%7C+str.replace+"%25#{str}%25"+}|code-block|syntax|javascript|764758|如果您希望哈希在适当的位置进行更改，但又不想影响字符串(您希望它获得新的字符串)：|764759|#+Two+ways+to+achieve+the+same+result+(any+Ruby+version)
my_hash.each{+%7Ckey,str%7C+my_hash[key]+=+"%25#{str}%25"+}
my_hash.inject(my_hash){+%7Ch,(k,str)%7C+h[k]="%25#{str}%25";+h+}|764760|如果你想要一个新的散列：|764761|#+Ruby+1.8.6%2B
new_hash+=+Hash[*my_hash.map{%7Ck,str%7C+[k,"%25#{str}%25"]+}.flatten]

#+Ruby+1.8.7%2B
new_hash+=+Hash[my_hash.map{%7Ck,str%7C+[k,"%25#{str}%25"]+}+]|764762|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

If you want the actual strings themselves to mutate in place (possibly and desirably affecting other references to the same string objects):

<pre><code># Two ways to achieve the same result (any Ruby version)
my_hash.each{ |_,str| str.gsub! /^|$/, '%' }
my_hash.each{ |_,str| str.replace "%#{str}%" }
</code></pre>

If you want the hash to change in place, but you don't want to affect the strings (you want it to get new strings):

<pre><code># Two ways to achieve the same result (any Ruby version)
my_hash.each{ |key,str| my_hash[key] = "%#{str}%" }
my_hash.inject(my_hash){ |h,(k,str)| h[k]="%#{str}%"; h }
</code></pre>

If you want a new hash:

<pre><code># Ruby 1.8.6+
new_hash = Hash[*my_hash.map{|k,str| [k,"%#{str}%"] }.flatten]

# Ruby 1.8.7+
new_hash = Hash[my_hash.map{|k,str| [k,"%#{str}%"] } ]
</code></pre>

blocks|key|764841|text|更具可读性的是，将其map到一个单元素散列数组中，并使用merge对其进行reduce|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|764842|the_hash.map{+%7Ckey,value%7C+{key+=>+"%25#{value}%25"}+}.reduce(:merge)|code-block|syntax|javascript|764843|entityMap^0|A|3|S|5|11|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

A bit more readable one, <code>map</code> it to an array of single-element hashes and <code>reduce</code> that with <code>merge</code>

<pre><code>the_hash.map{ |key,value| {key =&gt; "%#{value}%"} }.reduce(:merge)
</code></pre>

blocks|key|764867|text|在Ruby+2.1和更高版本中，您可以执行以下操作|type|unstyled|depth|inlineStyleRanges|entityRanges|data|764868|{+a:+'a',+b:+'b'+}.map+{+%7Ck,+str%7C+[k,+"%25#{str}%25"]+}.to_h|code-block|syntax|javascript|764869|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In Ruby 2.1 and higher you can do

<pre><code>{ a: 'a', b: 'b' }.map { |k, str| [k, "%#{str}%"] }.to_h
</code></pre>

blocks|key|764938|text|就地修改散列值的最佳方法是|type|unstyled|depth|inlineStyleRanges|entityRanges|data|764939|hash.update(hash){+%7C_,v%7C+"%25#{v}%25"+}|code-block|syntax|javascript|764940|代码更少，意图更清晰。速度也更快，因为除了必须更改的值之外，不会分配任何新对象。|764941|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The best way to modify a Hash's values in place is

<pre><code>hash.update(hash){ |_,v| "%#{v}%" }
</code></pre>

Less code and clear intent. Also faster because no new objects are allocated beyond the values that must be changed.

blocks|key|980335|text|这个任务有一个新的'Rails+way‘方法:)+http://api.rubyonrails.org/classes/Hash.html#method-i-transform_values|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|980336|entityMap|0|LINK|mutability|MUTABLE|url|http://api.rubyonrails.org/classes/Hash.html#method-i-transform_values^0|P|1Y|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

There is a new 'Rails way' method for this task :)
<a href="http://api.rubyonrails.org/classes/Hash.html#method-i-transform_values" rel="noreferrer">http://api.rubyonrails.org/classes/Hash.html#method-i-transform_values</a>

blocks|key|980376|text|在使用RSpec进行测试后，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|980377|describe+Hash+do
++describe+:map_values+do
++++it+'should+map+the+values'+do
++++++expect({:a+=>+2,+:b+=>+3}.map_values+{+%7Cx%7C+x+**+2+}).to+eq({:a+=>+4,+:b+=>+9})
++++end
++end
end|code-block|syntax|javascript|980378|您可以按如下方式实现Hash#map_values：|980379|class+Hash
++def+map_values
++++Hash[map+{+%7Ck,+v%7C+[k,+yield(v)]+}]
++end
end|980380|然后可以像这样使用该函数：|980381|{:a=>'a'+,+:b=>'b'}.map_values+{+%7Cv%7C+"%25#{v}%25"+}
#+{:a=>"%25a%25",+:b=>"%25b%25"}|980382|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

After testing it with RSpec like this:

<pre><code>describe Hash do
 describe :map_values do
 it 'should map the values' do
 expect({:a =&gt; 2, :b =&gt; 3}.map_values { |x| x ** 2 }).to eq({:a =&gt; 4, :b =&gt; 9})
 end
 end
end
</code></pre>

You could implement Hash#map_values as follows:

<pre><code>class Hash
 def map_values
 Hash[map { |k, v| [k, yield(v)] }]
 end
end
</code></pre>

The function then can be used like this:

<pre><code>{:a=&gt;'a' , :b=&gt;'b'}.map_values { |v| "%#{v}%" }
# {:a=&gt;"%a%", :b=&gt;"%b%"}
</code></pre>

blocks|key|980430|text|Ruby2.4引入了Hash#transform_values!方法，您可以使用它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|980431|{+:a=>'a'+,+:b=>'b'+}.transform_values!+{+%7Cv%7C+"%25#{v}%25"+}
#+=>+{:a=>"%25a%25",+:b=>"%25b%25"}+|code-block|syntax|javascript|980432|entityMap|0|LINK|mutability|MUTABLE|url|http://ruby-doc.org/core-2.4.0/Hash.html#method-i-transform_values-21^0|A|M|A|M|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Ruby 2.4 introduced the method <a href="http://ruby-doc.org/core-2.4.0/Hash.html#method-i-transform_values-21" rel="noreferrer"><code>Hash#transform_values!</code></a>, which you could use.

<pre><code>{ :a=&gt;'a' , :b=&gt;'b' }.transform_values! { |v| "%#{v}%" }
# =&gt; {:a=&gt;"%a%", :b=&gt;"%b%"} 
</code></pre>

blocks|key|980459|text|如果你想知道哪个inplace变量是最快的，这里就是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|980460|Calculating+-------------------------------------
inplace+transform_values!+1.265k+(±+0.7%25)+i/s+-++++++6.426k+in+++5.080305s
++++++inplace+update++++++1.300k+(±+2.7%25)+i/s+-++++++6.579k+in+++5.065925s
++inplace+map+reduce++++281.367++(±+1.1%25)+i/s+-++++++1.431k+in+++5.086477s
++++++inplace+merge!++++++1.305k+(±+0.4%25)+i/s+-++++++6.630k+in+++5.080751s
++++++++inplace+each++++++1.073k+(±+0.7%25)+i/s+-++++++5.457k+in+++5.084044s
++++++inplace+inject++++697.178++(±+0.9%25)+i/s+-++++++3.519k+in+++5.047857s|code-block|syntax|javascript|980461|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are curious which inplace variant is the fastest here it is:

<pre><code>Calculating -------------------------------------
inplace transform_values! 1.265k (± 0.7%) i/s - 6.426k in 5.080305s
 inplace update 1.300k (± 2.7%) i/s - 6.579k in 5.065925s
 inplace map reduce 281.367 (± 1.1%) i/s - 1.431k in 5.086477s
 inplace merge! 1.305k (± 0.4%) i/s - 6.630k in 5.080751s
 inplace each 1.073k (± 0.7%) i/s - 5.457k in 5.084044s
 inplace inject 697.178 (± 0.9%) i/s - 3.519k in 5.047857s
</code></pre>

I want to change every value in a hash so as to add '%' before and after the value so

<pre><code>{ :a=&gt;'a' , :b=&gt;'b' }
</code></pre>

must be changed to

<pre><code>{ :a=&gt;'%a%' , :b=&gt;'%b%' }
</code></pre>

What's the best way to do this?

Changing every value in a hash in Ruby

我想要更改散列中的每个值，以便在值之前和之后添加'%‘，因此{ :a=>'a' , :b=>'b' }必须更改为{ :a=>'%a%' , :b=>'%b%' }做这件事最好的方法是什么？

问在Ruby中更改散列中的每个值
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