CODEWITHSUNDEEP
ruby-on-railsarrays
John
John

Reputation: 1323

how to eliminate empty arrays from an array of arrays in ruby?

i have an array of arrays. from this i want to eliminate the empty arrays.

iam using reject!(&:empty?) method. but it is giving me unexpected results.

2.2.2 :306 >   array = ["yes","yes","yes"]
 => ["yes", "yes", "yes"] 
2.2.2 :307 > array.split("no")
 => [["yes", "yes", "yes"]] 
2.2.2 :308 > array.split("no").reject!(&:empty?)
 => nil 
2.2.2 :309 > array_with_no = ["yes","yes","yes","no"]
 => ["yes", "yes", "yes", "no"] 
2.2.2 :310 > array_with_no.split("no")
 => [["yes", "yes", "yes"], []] 
2.2.2 :311 > array.split("no").reject!(&:empty?)
 => nil 
2.2.2 :312 > array_with_no.split("no").reject!(&:empty?)
 => [["yes", "yes", "yes"]] 
2.2.2 :313 >

i want the result where when there is no empty array to eliminate, then it should return the same array instead of returning nil

Upvotes: 1

Views: 1787

Answers (4)

tekuri
tekuri

Reputation: 146

You can use delete_if: 

array = [["yes","yes","yes"], [], []]
array.delete_if{|x| x.empty?}

it will return [["yes","yes","yes"]

Or if you want to combine array of arrays you may use flatten:

array = ["yes","yes","yes"], [], []].flatten

it will return ["yes","yes","yes"]

Upvotes: 1

ruby_newbie
ruby_newbie

Reputation: 3275

Use select. 

array.split("no").select(&:present?)


=> [["yes", "yes", "yes"]]

Alternatively you can remove the bang from your reject and that will also give you what you want. 

array.split("no").reject(&:empty?)

=> [["yes", "yes", "yes"]]

The ! on reject! will destructively modify the array in place and will return nil if no changes were made.

Upvotes: 0

Thorin
Thorin

Reputation: 2034

If you need result in single dimension then you can use simply:

[["yes", "yes", "yes"], []].flatten.compact

Upvotes: 2

jfornoff
jfornoff

Reputation: 1368

You want reject instead of reject! (the !-version modifies the array in-place and returns true or nil depending on if changes to the array were made or not)

Documentation on what the methods do

Upvotes: 0

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