How to group and count occurrences of values in Elixir's list
Join Elixir newsletter
Subscribe to receive Elixir news to your inbox every two weeks.
Expand your skills
Download free e-books, watch expert tech talks, and explore open-source projects. Everything you need to grow as a developer - completely free.
If you ever had to count occurrences of values in Elixir's list, this short post might be helpful for you!
Let's assume that the input contains a list of people names:
people = [
%{name: "John"},
%{name: "Tom"},
%{name: "John"},
%{name: "David"}
]Our goal here is to count occurrences of names so that in the end we'll get this summary:
%{"David" => 1, "John" => 2, "Tom" => 1}In Elixir, it's super easy! You can use Enum.frequencies_by/2 to achieve that in a simple one-liner:
iex > Enum.frequencies_by(people, & &1.name)
%{"David" => 1, "John" => 2, "Tom" => 1}Work with a team that keeps learning and building better software every day.
Related posts
Dive deeper into this topic with these related posts
You might also like
Discover more content from this category
Learn a trick that will allow you to manage item order in Postgres tables easier & faster.
By default in the test env, Phoenix doesn't show Logger.debug/Logger.info outputs in the console.