8/12/2019 7 Daily Use Cases of Ruby Array

1/4

7 daily use cases of Ruby Array

7 Replies

Ruby and Ruby on Rails come with great reference documentation (Ruby doc,Rails doc, oralternatives such as APIdock, or the recent omnirefcovering also all gems) !ut when you

need to find how to check if one array has all elements of another, you won"t find the answer

in the doc because it"s not use case oriented #he documentation e$plains what each piece can

do, not how you can use it (and clearly not which you should use for a given use case) %f

course, that"s the same for tutorial and books &opefully, there is 'tack%verflow !elow, I

share 7 common use cases of Array I met very often and should be useful to you

1. How to check if one Array has all elements of another?

ou want to check that all imported emails already e$ist in a contact list

imported_emails = [ 'john@doe.com', 'janet@doe.com']existing_emails = [ 'john@doe.com', 'janet@doe.com', 'fred@mercury.com']

puts 'already imported'if(imported_emails - existing_emails.empty!

IR! %utput

already imported=" nil

Reference Array *ifference

2. How to find whats elements are common to two

Arrays?

ou want to find the common tags of two blog posts

tags_post# = [ 'ru$y', 'rails', 'test']tags_post% = [ 'test', 'rspec']

common_tags = tags_post# & tags_post%

IR! %utput

=" [test]

Reference 'et Intersection

3. How to merge two Arrays without dulicating entries?

ou want to get a uni+ue list of twitter accounts id followed by two persons

folloeds# = [ #, %, )]

http://blog.8thcolor.com/2014/02/7-daily-use-cases-of-ruby-array/#commentshttp://ruby-doc.org/http://api.rubyonrails.org/http://api.rubyonrails.org/http://apidock.com/http://www.omniref.com/http://www.ruby-doc.org/core-2.1.0/Array.html#method-i-2Dhttp://www.ruby-doc.org/core-2.1.0/Array.html#method-i-26http://blog.8thcolor.com/2014/02/7-daily-use-cases-of-ruby-array/#commentshttp://ruby-doc.org/http://api.rubyonrails.org/http://apidock.com/http://www.omniref.com/http://www.ruby-doc.org/core-2.1.0/Array.html#method-i-2Dhttp://www.ruby-doc.org/core-2.1.0/Array.html#method-i-26

8/12/2019 7 Daily Use Cases of Ruby Array

2/4

folloeds% = [ %, *, +]

all_folloeds = folloeds# folloeds%

IR! %utput

=" [#, %, ), *, +]

Reference 'et -nion

!. How to sort an Array of Hashes?

ou retrieve data from a third party API that returns an Array of &ashes as following

data = [

name '/hristophe', location '0elgium'1, name '2ohn', location '3nited 4tates of 5merica'1, name '6iet', location '0elgium'1, name '7ran8ois',

location '7rance'1]

.hen displaying those data, you want to sort them by location ou can do it with

data.sort_$y hsh hsh[location] 1

IR! %utput

=" [ name="/hristophe, location="0elgium1,

name="6iet, location="0elgium1, name="7ran8ois, location="7rance1, name="2ohn, location="3nited 4tates of 5merica1 ]

Reference /numerable0sort1by

". How to kee ob#ects in an Array that are uni$ue with

resect to one attribute?

In an online shop, on the home page, you need to show one product per category

6roduct = 4truct.ne(id, category_id

2

http://www.ruby-doc.org/core-2.1.0/Array.html#method-i-7Chttp://www.ruby-doc.org/core-2.1.0/Enumerable.html#method-i-sort_byhttp://www.ruby-doc.org/core-2.1.0/Array.html#method-i-7Chttp://www.ruby-doc.org/core-2.1.0/Enumerable.html#method-i-sort_by

8/12/2019 7 Daily Use Cases of Ruby Array

3/4

products = [6roduct.ne(#, #,6roduct.ne(%, %,6roduct.ne(), ),6roduct.ne(*, #,

6roduct.ne(+, ),6roduct.ne(9, +,]

products = products.uni: &category_id

IR! %utput

=" [ ;utorial earn He$ FeIelopment ith ?ails]

Reference /numerable0grep

7. How to always get an Array?

In a method you work with products and you eventually return one or several !ut when you

get only one, it"s not an Array ou can deal very smoothly with both cases with Array() or

345

defmethod; K

[Lproducts]

6

http://www.ruby-doc.org/core-2.1.0/Array.html#method-i-uniqhttp://ruby-doc.org/core-2.1.0/Enumerable.html#method-i-grephttp://www.ruby-doc.org/core-2.1.0/Array.html#method-i-uniqhttp://ruby-doc.org/core-2.1.0/Enumerable.html#method-i-grep

8/12/2019 7 Daily Use Cases of Ruby Array

4/4

end

ou"ll find more e$planations in the !ohidar !atsov"s post

Reference 8ernel0Array,splat operator,Ruby 'tyle guide

'hats your daily use cases of Array?

Ruby is full of treasures It takes some times to know them and find how you can use them

.hat"s yours9 .hat are your typical daily use cases of Array and beautiful Ruby to resolve

them9

:

http://batsov.com/articles/2013/06/28/the-elements-of-style-in-ruby-number-3-make-sure-something-is-an-array/http://www.ruby-doc.org/core-2.1.0/Kernel.html#method-i-Arrayhttp://www.ruby-doc.org/core-2.1.0/doc/syntax/calling_methods_rdoc.html#label-Array+to+Arguments+Conversionhttp://www.ruby-doc.org/core-2.1.0/doc/syntax/calling_methods_rdoc.html#label-Array+to+Arguments+Conversionhttp://www.ruby-doc.org/core-2.1.0/doc/syntax/calling_methods_rdoc.html#label-Array+to+Arguments+Conversionhttps://github.com/bbatsov/ruby-style-guidehttp://batsov.com/articles/2013/06/28/the-elements-of-style-in-ruby-number-3-make-sure-something-is-an-array/http://www.ruby-doc.org/core-2.1.0/Kernel.html#method-i-Arrayhttp://www.ruby-doc.org/core-2.1.0/doc/syntax/calling_methods_rdoc.html#label-Array+to+Arguments+Conversionhttps://github.com/bbatsov/ruby-style-guide