convert array to hash and initialize to a value

Question

what is the best way to convert an array of

arr = ["one", "two", "three", "four", "five"]

to hash of

{"one"=>0, "two"=>0, "three"=>0, "four"=>0, "five"=>0}

Iam planning to fillup the '0' with my own values later, I just need the technique now.

Thanks.

Cary Swoveland · Accepted Answer · 2015-05-28 05:31:02Z

5

arr.product([0]).to_h

or for versions < 2.0

Hash[arr.product([0])]

answered May 28, 2015 at 5:31

Cary Swoveland

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Kimball · Accepted Answer · 2015-05-28 05:01:15Z

5

I don't know if it's the best way:

Hash[arr.map{ |el| [el, 0] }]

answered May 28, 2015 at 5:01

Kimball

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spickermann · Accepted Answer · 2015-05-28 05:01:35Z

3

I would do this:

arr.inject({}) { |hash, key| hash.update(key => 0) }

answered May 28, 2015 at 5:01

spickermann

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errata · Accepted Answer · 2015-05-28 05:21:17Z

2

Hash[ *arr.collect { |v| [ v, 0 ] }.flatten ]

answered May 28, 2015 at 5:21

errata

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1 Comment

Kimball Over a year ago

per some very rough benchmarks, of those posted, this one seems to be the fastest for single large arrays, but lags behind when dealing with large numbers of small arrays.

FloatingRock · Accepted Answer · 2017-03-29 10:59:21Z

0

You can also do

arr.each_with_object({}) {|v, h| h[v] = 1}

where:

v is the value of each element in the array,
h represents the hash object

answered Mar 29, 2017 at 10:59

FloatingRock

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