counter (list items[, function f]) ⇒ map
Generates a map which contains the count of all instances of each value from the items array. If a function is supplied to this, each item will be passed to the function first.
First available: Version 1.4.1.0
Using counter
Using a function is useful when you are working with an array of arrays,
since the function compares based on the value as a whole. Given
some lambda function, only a part of the inner arrays could be
returned and processed. The counter function supports the optional f
parameter.
The following example is a standard use of counter.
YASS
function main($args) //This variable used to be called $list, but since ZPE 1.5, list is a reserved keyword and cannot be used $l = [["Ashley", 32], ["Jonathan", 64], ["Adam", 12], ["Jamie", 32], ["Frank", 64]] //By passing this to the function, we can return the second index (index 1) from the inner list and count that $counted = counter($l, function($x) return list_get_at_index ($x, 1) end function) //Should return [12 => 1, 64 => 2, 32 => 2] print($counted) end function
It can also be used nicely with object instances to count properties of them:
YASS
struct person $fname = "" $sname = "" $grade = "" function _construct($f, $s, $g) this->$fname = $f this->$sname = $s this->$grade = $g end function public function getGrade() return this->$grade end function end struct function main() $p1 = new person("Ashley", "Peters", "C") $p2 = new person("James", "Peters", "A") $p3 = new person("Frank", "Adams", "B") $p4 = new person("Ashley", "Adams", "A") $p5 = new person("Jamie", "Bond", "A") $p6 = new person("Alec", "Bond", "C") $people = [$p1, $p2, $p3, $p4, $p5, $p6] //Should result in [A => 3, B => 1, C => 2] $result = counter($people, function($x) return $x->getGrade() end function) print($result) //Should print 3 print($result["A"]) end function
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