Re: Using each_with_object or inject with a hash object

Thanks. It makes sense. I should have looked at Hash.new documentation.

The block is yielded but the value is never assigned to the key.
{ Array.new } Vs {|h,k| h[k] = Array.new }

- Adi

On Tue, Mar 26, 2019 at 3:11 PM Brandon Weaver <[email protected]>
wrote:

> Hash.new { ¦h, k¦ h[k] = [] }
>
> This might help: https://link.medium.com/HGYloiBCnV
>
> On Tue, Mar 26, 2019, 1:03 PM adithya pentela <[email protected]>
> wrote:
>
>> Hello,
>>
>> I'm trying to use each_with_object with a hash initialized using the
>> Hash.new syntax with an implicit block.
>> I'm expecting an empty array to be initialized whenever I attempt to
>> access a new key but my results are a bit different. I looked at the
>> Enumerable documentation but could not find an answer.
>>
>> It'll be great if someone can shed some light on what is going on.
>>
>> Here's the code:
>>
>> ary = Array.new(10) { [rand(100), rand(100)] }
>> memo = Hash.new { Array.new }
>>
>>
>> ary.inject(memo) { |hsh,(i,j)| hsh[i] << j; hsh }
>>
>> >> {}
>>
>>
>> ary.each_with_object(memo) { |(i,j),hsh| hsh[i] << j }
>>
>> >> {}
>>
>>
>> ary.inject({}) { |hsh,(i,j)| hsh[i] ||= []; hsh[i] << j ; hsh }
>>
>> >> {k: [v1, v2]}
>>
>>
>> ary.each_with_object({}) { |(i,j),hsh| hsh[i] ||= []; hsh[i] << j }
>> >> {k: [v1, v2]}
>>
>>
>> Thanks,
>> Adi
>>
>>
>>
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