flatten.hhs

/**
 * @author Jason Reynolds
 * @param input - The multidimensional (or not) array to flatten
 * @returns A 1d array that represents the input 'flattened'. Not returning Mat because Mat forces 2d
 * 
 * Function wrapper mathjs for flattening a multi dim matrix into a 1d matrix/array
 * 
 * 
 */



function flatten(input) {

    *import math: ndim
    *import math: deep_copy
    *import math: is_number

    if (arguments.length === 0) {
        throw new Error('Exception occurred in flatten - no argument given');
    }
    else if (arguments.length !== 1) {
        throw new Error('Exception occurred in flatten - wrong argument number');
    }

    if (is_number(input)) {
        return [input];
    }

    if (!(Array.isArray(input)) && !(input instanceof Mat) && !(input instanceof Tensor)) {
        throw new Error('Exception occurred in flatten - input must be a number, array, matrix or tensor');
    }

    //declare raw_input to be a clone of input when input is a Mat or Tensor, otherwise input itself
    let in_type = (input instanceof Mat || input instanceof Tensor);
    let raw_input = (in_type) ? input.clone() : deep_copy(input);

    //when it is a clone, degrade it to vanilla array to use as argument for JS function
    if (input instanceof Mat || input instanceof Tensor) {
        raw_input = raw_input.val;
        //return the result of mathjs.flatten
        return mathjs.flatten(raw_input);
    }
    //when its a number... create an empty array, push input into it and return that array of length 1
    //when its a 1d array, you can't flatten it so return itself
    else if (ndim(input) === 1) {
        return input;
    }
    //when ndim = 2 or higher and not instanceof Mat or Tensor, then it's JS array so return it through mathjs.flatten
    else {
        return mathjs.flatten(raw_input);
    }
}