first
The first filter returns the first element of an array, hash or string.
Array
{{ [1, 2, 3, 4]|first }}
The above will output: 1.
Hash
{{ {'name': 'Sam', 'age': 55}|first }}
String
{{ 'Bob Hope'|first }}
The above will output "B"
Assignment
As with all filters, you can use the first filter when assigning a variable.
{% set name = 'Bob Hope' %}
{% set letter = name|first %}