countAs - nodef/extra-entries GitHub Wiki

Count occurrences of values.

Alternatives: count, countAs.

function countAs(x, fm)
// x:  entries
// fm: map function (v, k, x)
const entries = require('extra-entries');

var x = ["a", 1], ["b", 1], ["c", 2], ["d", 2], ["e", 4](/nodef/extra-entries/wiki/"a",-1],-["b",-1],-["c",-2],-["d",-2],-["e",-4);
entries.countAs(x);
// → Map(3) { 1 => 2, 2 => 2, 4 => 1 }

var x = ["a", 1], ["b", 2], ["c", 3], ["d", 4](/nodef/extra-entries/wiki/"a",-1],-["b",-2],-["c",-3],-["d",-4);
entries.countAs(x, v => v % 2);
// → Map(2) { 1 => 2, 0 => 2 }

References