ruby 如何通过数字索引获取哈希值
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How to get a hash value by numeric index
提问by Lesha Pipiev
Have a hash:
有一个哈希：
h = {:a => "val1", :b => "val2", :c => "val3"}
I can refer to the hash value:
我可以参考哈希值：
h[:a], h[:c]
but I would like to refer by numeric index:
但我想通过数字索引来引用：
h[0] => val1
h[2] => val3
Is it possible?
是否可以？
回答by Aleksei Matiushkin
h.valueswill give you an array requested.
h.values会给你一个请求的数组。
> h.values
# ? [
# [0] "val1",
# [1] "val2",
# [2] "val3"
# ]
UPDwhile the answer with h[h.keys[0]]was marked as correct, I'm a little bit curious with benchmarks:
UPD虽然答案h[h.keys[0]]被标记为正确，但我对基准有点好奇：
h = {:a => "val1", :b => "val2", :c => "val3"}
Benchmark.bm do |x|
x.report { 1_000_000.times { h[h.keys[0]] = 'ghgh'} }
x.report { 1_000_000.times { h.values[0] = 'ghgh'} }
end
#
# user system total real
# 0.920000 0.000000 0.920000 ( 0.922456)
# 0.820000 0.000000 0.820000 ( 0.824592)
Looks like we're spitting on 10% of productivity.
看起来我们在吐槽 10% 的生产力。
回答by saihgala
h = {:a => "val1", :b => "val2", :c => "val3"}
keys = h.keys
h[keys[0]] # "val1"
h[keys[2]] # "val3"
回答by Intrepidd
So you need both array indexing and hash indexing ?
所以你需要数组索引和哈希索引？
If you need only the first one, use an array.
如果您只需要第一个，请使用数组。
Otherwise, you can do the following :
否则，您可以执行以下操作：
h.values[0]
h.values[1]
