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42 lines
1.1 KiB
Markdown
42 lines
1.1 KiB
Markdown
# Exclude Values From An Array
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In true Ruby fashion, there are all sorts of ways to exclude values from an
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array.
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If you just want to exclude `nil` values, you can use
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[`#compact`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-compact).
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```ruby
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> [1,nil,:what,4].compact
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#=> [1, :what, 4]
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```
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If you want to exclude `nil` values and some other named value, you could use
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[`#filter`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-filter) or
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[`#reject`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-reject).
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```ruby
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> [1,nil,:what,4].filter { |val| !val.nil? && val != :what }
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#=> [1, 4]
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> [1,nil,:what,4].reject { |val| val.nil? || val == :what }
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#=> [1, 4]
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```
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The filter is clumsy and heavy-handed for this sort of example. A really terse
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way of doing the same thing is with set difference:
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[`#-`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-2D).
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```ruby
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> [1,nil,:what,nil,5] - [:what,nil]
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#=> [1, 5]
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```
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Or the spelled out
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[`#difference`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-difference)
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method.
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```ruby
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> [1,nil,:what,nil,5].difference([:what,nil])
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#=> [1, 5]
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```
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