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stdlib/lib/node_modules/@stdlib/utils/tabulate at develop · stdlib-js/stdlib

Generate a frequency table.

Usage

var tabulate = require( '@stdlib/utils/tabulate' );

tabulate( collection )

Generates a frequency table.

var arr = [ 'beep', 'boop', 'foo', 'beep' ];

var out = tabulate( arr );
// returns [ [ 'beep', 2, 0.5 ], [ 'boop', 1, 0.25 ], [ 'foo', 1, 0.25 ] ]

The returned frequency table is an array of arrays. Each sub-array corresponds to a unique value in the input collection and is structured as follows:

  • 0: unique value.
  • 1: value count.
  • 2: frequency percentage.

Notes

  • A collection may be either an Array, Typed Array, or an array-like Object (excluding strings and functions).

Examples

var randu = require( '@stdlib/random/base/randu' );
var floor = require( '@stdlib/math/base/special/floor' );
var tabulate = require( '@stdlib/utils/tabulate' );

var vals;
var arr;
var out;
var i;
var j;

vals = [ 'beep', 'boop', 'foo', 'bar', 'woot', 'woot' ];

// Generate a random collection...
arr = new Array( 100 );
for ( i = 0; i < arr.length; i++ ) {
    j = floor( randu()*vals.length );
    arr[ i ] = vals[ j ];
}

// Generate a frequency table:
out = tabulate( arr );
console.log( out );

See Also