JavaScript Array Manipulations

August 31, 2024

This content originally appeared on DEV Community and was authored by Jamilah Foucher

Manipulating 2d, 3d, or 4d arrays in JavaScript are necessary for AI model training and image/audio/video analysis.

Below are a few useful functions for array manipulation using pure JavaScript without matrix packages like Tensorflow.js.

Transpose of a 2d array

function transpose_2d_array(arr) {

    var transpose_colNum = arr.length;
    var transpose_rowNum = arr.at(0).length;
    var transpose_arr = [];
    for (var i=0; i<transpose_rowNum ; i++) {
        const col = Array.from({ length: transpose_colNum }, (_, i) => 0);
        transpose_arr.push(col);
    }

    for (var i=0; i<arr.length; i++) {
        for (var j=0; j<arr.at(i).length; j++) {
            transpose_arr[j][i] = arr[i][j];
        }
    }
    return transpose_arr;
}

Print the Shape of an array

async function recur_func(arr) {
    if (arr != undefined) {
        return [arr[0], arr.length];
    } else {
        return arr;
    }
}

async function shape(arr) {
    var out = await recur_func(arr);
    var shap = [out[1]];
    var c = 0; // typically work with 4D arrays or less
    while (out != undefined && c < 4) {
        out = await recur_func(out[0]);
        if (out != undefined) {
            shap.push(out[1]);
        }
        c = c + 1;
    }
    return shap.slice(0, shap.length-1);
}

I hope these array utility functions will be helpful to someone.

Happy practicing!

This content originally appeared on DEV Community and was authored by Jamilah Foucher

JavaScript