brendan.mcdevitt.tech/_programming/2019-02-05-ruby2.6+-array#difference.markdown

layout	title	date	categories
programming	Ruby 2.6+ Array#Difference	2019-02-05	programming

Array#Difference - Array#Difference

I wanted to do a quick post on a new method added to ruby Array class in version 2.6. I just learned about this over the past weekend. This will quickly grow to be a favorite of mine.

A method to check differences in values between two arrays.

Make arrays abc and abcdef

{% highlight ruby %} [1] pry(main)> abc = ['a','b','c'] => ["a", "b", "c"]

[2] pry(main)> abcdef = 'a', 'b', 'c', 'd', 'e', 'f' => ["a", "b", "c", "d", "e", "f"] {% endhighlight %}

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ruby 2.5

In versions prior, I would make a .difference method in my .pryrc file and that will be loaded at runtime when I run my console. You can also monkey patch it live in a pry console. Found this via stackedoverflow post. Here is how I would add it in a running pry session:

{% highlight ruby %} [17] pry(main)> class Array [17] pry(main)* def difference(a) [17] pry(main)* self - a | a - self [17] pry(main)* end
[17] pry(main)* end
=> :difference

[26] pry(main)> abcdef.difference(abc) => ["d", "e", "f"]

{% endhighlight %}

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ruby 2.6

But now in ruby 2.6+, you can just use the .difference method. It is built into the class now.

{% highlight ruby %} [3] pry(main)> abcdef.difference(abc) => ["d", "e", "f"] {% endhighlight %}

so nice, so easy!