How to extract only needed attribute from an array

[Thriving K.]

I have an object called Tags with id and name ==> [ tag.id , tag.name]

| [1 , aaa] |

| [ 3 , bbb] |

| [ 5 , ccc] |

| [ 6 , dfd] |

| [ 7 , waf] |

| [ 11 , vee] |

There is an array with the list of tags , i just want to extract all
tag.id
as a new array, what is the easiest way to do

 

[Gennady Bystritsky]

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[Joel VanderWerf]

I have an object called Tags with id and name ==> [ tag.id , tag.name]

| [1 , aaa] |

| [ 3 , bbb] |

| [ 5 , ccc] |

| [ 6 , dfd] |

| [ 7 , waf] |

| [ 11 , vee] |

There is an array with the list of tags , i just want to extract all
tag.id
as a new array, what is the easiest way to do

Is this how your array looks?

a = [
[1 , :aaa],
[ 3 , :bbb],
[ 5 , :ccc],
[ 6 , :dfd],
[ 7 , :waf],
[ 11 , :vee]
]

p a.transpose[0] # ==> [1, 3, 5, 6, 7, 11]

Or:

p a.map {|b| b[0]}

 

[Brian Candler]

p a.transpose[0] # ==> [1, 3, 5, 6, 7, 11]

Or:

p a.map {|b| b[0]}

Or:

p a.map {|(id,name)| id }

 

[Thriving K.]

Thank you for everyone

 

[Robert Klemme]

I have an object called Tags with id and name =3D=3D> [ tag.id , tag.name= ]

| [1 , aaa] =A0 |

| [ 3 , bbb] =A0|

| [ 5 , ccc] =A0|

| [ 6 , dfd] =A0|

| [ 7 , waf] =A0|

| [ 11 , vee] |

There is an array with the list of tags , i just want to extract all
tag.id
as a new array, what is the easiest way to do

In any case you need method #map. In 1.9* you can even do use map(&:id):

irb(main):001:0> Tag =3D Struct.new :id, :name
=3D> Tag
irb(main):002:0> a =3D Array.new(5) {|i| Tag.new(i, "n"*i)}
=3D> [#<struct Tag id=3D0, name=3D"">, #<struct Tag id=3D1, name=3D"n">,
#<struct Tag id=3D2, name=3D"nn">, #<struct Tag id=3D3, name=3D"nnn">,
#<struct Tag id=3D4, name=3D"nnnn">]
irb(main):003:0> a.map(&:id)
=3D> [0, 1, 2, 3, 4]

Kind regards

robert


--=20
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