# Exclude Values From An Array

In true Ruby fashion, there are all sorts of ways to exclude values from an array.

If you just want to exclude `nil` values, you can use [`#compact`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-compact).

```ruby
> [1,nil,:what,4].compact
#=> [1, :what, 4]
```

If you want to exclude `nil` values and some other named value, you could use [`#filter`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-filter) or [`#reject`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-reject).

```ruby
> [1,nil,:what,4].filter { |val| !val.nil? && val != :what }
#=> [1, 4]
> [1,nil,:what,4].reject { |val| val.nil? || val == :what }
#=> [1, 4]
```

The filter is clumsy and heavy-handed for this sort of example. A really terse way of doing the same thing is with set difference: [`#-`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-2D).

```ruby
> [1,nil,:what,nil,5] - [:what,nil]
#=> [1, 5]
```

Or the spelled out [`#difference`](https://ruby-doc.org/core-3.0.0/Array.html#method-i-difference) method.

```ruby
> [1,nil,:what,nil,5].difference([:what,nil])
#=> [1, 5]
```


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