How to create a hash from 2 arrays?

ruby-talk
1

keys = ["1", "2", "3", "4", "5"]
vals = ["a", "b", "c", "d", "e", "f", "g"]

I want h = {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

right now I do it by:
  for i in 0..keys.size-1
    h[keys[i]]=vals[i]
  end

is there a ruby way, more slick way of doing this? Thanks.

2

Hash[*keys.zip(vals).flatten]
#=> {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

···

On 10/17/05, Tiggerius <tiggerius@gmail.com> wrote:

keys = ["1", "2", "3", "4", "5"]
vals = ["a", "b", "c", "d", "e", "f", "g"]

I want h = {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

right now I do it by:
  for i in 0..keys.size-1
    h[keys[i]]=vals[i]
  end

is there a ruby way, more slick way of doing this? Thanks.

--
Simon Strandgaard

3

Not as slick as simons version, but never miss a possibility to use inject.

irb(main):001:0> keys = ["1", "2", "3", "4", "5"]
=> ["1", "2", "3", "4", "5"]

irb(main):002:0> vals = ["a", "b", "c", "d", "e", "f", "g"]
=> ["a", "b", "c", "d", "e", "f", "g"]

irb(main):003:0> keys.zip(vals).inject({}) { | h, (k, v) | h[k] = v; h }
=> {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

regards,

Brian

···

On 17/10/05, Tiggerius <tiggerius@gmail.com> wrote:

keys = ["1", "2", "3", "4", "5"]
vals = ["a", "b", "c", "d", "e", "f", "g"]

I want h = {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

right now I do it by:
  for i in 0..keys.size-1
    h[keys[i]]=vals[i]
  end

is there a ruby way, more slick way of doing this? Thanks.

--
http://ruby.brian-schroeder.de/

Stringed instrument chords: http://chordlist.brian-schroeder.de/

4

Tiggerius wrote:

keys = ["1", "2", "3", "4", "5"]
vals = ["a", "b", "c", "d", "e", "f", "g"]

I want h = {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

right now I do it by:
  for i in 0..keys.size-1
    h[keys[i]]=vals[i]
  end

is there a ruby way, more slick way of doing this? Thanks.

Array#zip is a good way to get started. It takes two Arrays and
'zips' them together: [1].zip([2]) => [[1, 2]]. #inject can be
used to accumulate data, here we accumulate into the Hash (which
is the initial {} there):

   keys.zip(values).inject({}) {|hash, (k, v)| hash[k] = v; hash}

An alternative syntax would leverage the ability of Hash. to
take an even number of parameters and construct its keys and
values from that: Hash[1, 2] => {1 => 2}. To create separate
parameters from the contents of an Array, use the splat-operator
(*): *[1, 2] => 1, 2:

   Hash[*keys.zip(values).flatten]

This only works when you do not have nested Arrays, though.

E

5

thanks. let me chew on it.

6

Brian Schröder wrote:

···

On 17/10/05, Tiggerius <tiggerius@gmail.com> wrote:

keys = ["1", "2", "3", "4", "5"]
vals = ["a", "b", "c", "d", "e", "f", "g"]

I want h = {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

right now I do it by:
  for i in 0..keys.size-1
    h[keys[i]]=vals[i]
  end

is there a ruby way, more slick way of doing this? Thanks.

Not as slick as simons version, but never miss a possibility to use
inject.

irb(main):001:0> keys = ["1", "2", "3", "4", "5"]
=> ["1", "2", "3", "4", "5"]

irb(main):002:0> vals = ["a", "b", "c", "d", "e", "f", "g"]
=> ["a", "b", "c", "d", "e", "f", "g"]

irb(main):003:0> keys.zip(vals).inject({}) { | h, (k, v) | h[k] = v;
h } => {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}

Very nice! You clearly seem injected - pardon: infected.
:slight_smile:

    robert