# Extract common entries in two arrays

**URL:** <https://www.ruby-forum.com/t/extract-common-entries-in-two-arrays/162878>\
**Category:** Ruby\
**Created:** [March 15, 2009, 12:32am UTC](https://www.ruby-forum.com/t/extract-common-entries-in-two-arrays/162878 "2009-03-15T00:32:36Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\
**Post date:** [March 15, 2009, 12:32am UTC](https://www.ruby-forum.com/t/extract-common-entries-in-two-arrays/162878/1 "2009-03-15T00:32:36Z")

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Hi, how to get an array with just common entries from two arrays?:

array1 = [“q”, “w”, “e”, “r”, “t”, “y”]  
array2 = [“w”, “t”, “z”]

I want to get:

array\_common = [“w”, “t”]

I don0t find an ellegant and fast way to get it. Any help?  
Thanks a lot.

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**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\
**Post date:** [March 15, 2009, 12:38am UTC](https://www.ruby-forum.com/t/extract-common-entries-in-two-arrays/162878/2 "2009-03-15T00:38:27Z")

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El Domingo, 15 de Marzo de 2009, Iñaki Baz C. escribió:

> Hi, how to get an array with just common entries from two arrays?:
> 
> array1 = [“q”, “w”, “e”, “r”, “t”, “y”]  
> array2 = [“w”, “t”, “z”]
> 
> I want to get:
> 
> array\_common = [“w”, “t”]

array\_common = array1 - (array1 - array2)  
=\> [“w”, “t”]

🙂

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**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\
**Post date:** [March 15, 2009, 12:40am UTC](https://www.ruby-forum.com/t/extract-common-entries-in-two-arrays/162878/3 "2009-03-15T00:40:48Z")

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On Sat, Mar 14, 2009 at 4:34 PM, Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> > array1 = [“q”, “w”, “e”, “r”, “t”, “y”]  
> > array2 = [“w”, “t”, “z”]
> > 
> > I want to get:  
> > array\_common = [“w”, “t”]
> 
> array\_common = array1 - (array1 - array2)  
> =\> [“w”, “t”]

Easier:

array1 & array2  
=\> [“w”, “t”]

Ben

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<div class="post-metadata">

**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\
**Post date:** [March 15, 2009, 12:42am UTC](https://www.ruby-forum.com/t/extract-common-entries-in-two-arrays/162878/4 "2009-03-15T00:42:33Z")

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El Domingo, 15 de Marzo de 2009, Ben B.  
escribió:\> Easier:

> array1 & array2  
> =\> [“w”, “t”]

Great!

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**Author:** ![ISSSSaki\_Baz\_C](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/51bf81/32.png) [@ISSSSaki\_Baz\_C](https://www.ruby-forum.com/u/ISSSSaki_Baz_C)\
**Post date:** [March 15, 2009, 2:10am UTC](https://www.ruby-forum.com/t/extract-common-entries-in-two-arrays/162878/5 "2009-03-15T02:10:19Z")

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On Sun, Mar 15, 2009 at 8:29 AM, Iñaki Baz C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Thanks a lot.
> 
> –  
> Iñaki Baz C.

array1 & array2

Harry