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

Question

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

you need multidimensional array always ?, or result may be in single dimensional array ? — Thorin
– Thorin, Commented May 9, 2016 at 12:36

Thorin · Accepted Answer · 2016-05-09 12:38:22Z

2

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

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

answered May 9, 2016 at 12:38

Thorin

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franiis · Accepted Answer · 2018-09-12 05:54:30Z

1

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"]

edited Sep 12, 2018 at 5:54

franiis

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answered Sep 12, 2018 at 4:16

tekuri

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jfornoff · Accepted Answer · 2016-05-09 12:27:47Z

0

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

answered May 9, 2016 at 12:27

jfornoff

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ruby_newbie · Accepted Answer · 2016-05-09 16:17:53Z

0

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.

edited May 9, 2016 at 16:17

answered May 9, 2016 at 15:42

ruby_newbie

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