Group element indices as arrays associated with distinct keys.
var groupIndices = require( '@stdlib/array/base/group-indices' );Groups element indices as arrays associated with distinct keys.
var x = [ 'beep', 'boop', 'foo', 'bar' ];
var groups = [ 'b', 'b', 'f', 'b' ];
var out = groupIndices( x, groups );
// returns { 'b': [ 0, 1, 3 ], 'f': [ 2 ] }-
Each value in
groupsshould resolve to a value which can be serialized as an object key. As a counterexample,var x = [ 'beep', 'boop', 'foo', 'bar' ]; var groups = [ {}, {}, {}, {} ]; var out = groupIndices( x, groups ); // returns { '[object Object]': [ 0, 1, 2, 3 ] }
while each "group" is unique, all input array elements resolve to the same group because each group identifier serializes to the same string.
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var take = require( '@stdlib/array/base/take-indexed' );
var groupIndices = require( '@stdlib/array/base/group-indices' );
// Define an initial array of values:
var values = [ 'beep', 'boop', 'foo', 'bar', 'woot', 'woot' ];
// Sample from the initial array to generate a random collection:
var indices = discreteUniform( 100, 0, values.length-1, {
'dtype': 'generic'
});
var x = take( values, indices );
// returns [...]
// Randomly assign collection values to groups:
var groups = discreteUniform( x.length, 0, values.length, {
'dtype': 'generic'
});
// Group the values:
var out = groupIndices( x, groups );
// returns {...}
console.log( out );