Remove nil and blank string in an array in Ruby

问题:

I am new to Ruby and stuck with this issue. Let's say I have an array like this:

arr = [1, 2, 's', nil, '', 'd']

and I want to remove nil and blank string from it, i.e. final array should be:

arr = [1, 2, 's', 'd']

I tried compact but it gives this:

arr.compact!
arr #=> [1, 2, 's', '', 'd'] doesn't remove empty string.

I was wondering if there's a smart way of doing this in Ruby.

回答1:

You could do this:

arr.reject { |e| e.to_s.empty? } #=> [1, 2, "s", "d"]

Note nil.to_s => ''.

回答2:

Since you want to remove both nil and empty strings, it's not a duplicate of How do I remove blank elements from an array?

You want to use .reject:

arr = [1, 2, 's', nil, '', 'd']
arr.reject { |item| item.nil? || item == '' }

NOTE: reject with and without bang behaves the same way as compact with and without bang: reject! and compact! modify the array itself while reject and compact return a copy of the array and leave the original intact.

If you're using Rails, you can also use blank?. It was specifically designed to work on nil, so the method call becomes:

arr.reject { |item| item.blank? }

回答3:

I tend to do:

arr = [1, 2, 's', nil, '', 'd']
arr.reject(&:blank?)

returns:

=> [1, 2, "s", "d"]

回答4:

You can also use - to remove all nil and '' elements:

arr -= [nil, '']
#=> [1, 2, "s", "d"]

Demonstration

Or compact and reject with shortcut (in case you are not using Rails where you can just use arr.reject(&:blank?) ):

arr = arr.compact.reject(&''.method(:==))
#=> [1, 2, "s", "d"]

Demonstration

回答5:

You can use compact with reject

arr = [1, 2, 's', nil, '', 'd']
arr = [1, 2, 's', 'd']

arr = arr.compact.reject { |h| h == "" }

or

arr = arr.compact.delete_if { |h| h == "" }

回答6:

arr.reject(&:blank?)

Just use this, no need to anything else.

回答7:

You can use compact and delete_if method to remove nil and blank string in an array in Ruby

arr = [1, 2, 's', nil, '', 'd']
arr.compact!.delete_if{|arrVal| arrVal.class == String and arrVal.empty?}
=> [1, 2, "s", "d"]

回答8:

The simplest and fast way of doing this is :

arr = [1, 2, 's', nil, '', 'd'] - [nil,'']

==> arr = [1, 2, 's', 'd']

回答9:

try this out:

[1, 2, "s", nil, "", "d"].compact.select{|i| !i.to_s.empty?}

回答10:

Note: I am considering the array might have string with white spaces in it.

You can do:

arr = [1, 2, 's', nil, ' ', 'd']
arr.reject{|a| a.nil? || (a.to_s.gsub(' ', '') == '') }
#=> [1, 2, "s", "d"]

or:

arr.reject{|a| a.nil? || (a.to_s.gsub(' ', '').empty?) }
#=> [1, 2, "s", "d"]

or if you want to update arr object itself then:

arr.reject!{|a| a.nil? || (a.to_s.gsub(' ', '') == '') } # notice the ! mark, it'll update the object itself.
p arr #=> [1, 2, "s", "d"]

回答11:

Hope this will work for your case :

arr = [1, 2, 's', nil, '', 'd']
arr.select{|x| x.to_s!="" }

回答12:

I would probably add .strip to eliminate potential whitespace headaches (assuming its not a rails app).

array = [1, 2, "s", nil, "     ", "d", "\n"]
array.reject!{|a| a.nil? || (a.to_s.strip.empty?) }

#=> [1, 2, "s", "d"]