Create Vertical Radio Buttons

.block

height: 100
scrolling: no
border: no

index.html

<script defer src=https://cdn.JsDelivr.net/npm/p5></script>
<script defer src=sketch.js></script>

sketch.js

/**
 * Create Vertical Radio Buttons (v1.0.1)
 * GoToLoop (2019-Apr-07)
 *
 * https://Discourse.Processing.org/t/
 * how-to-organize-radio-buttons-in-separate-lines/10041/5
 *
 * https://Bl.ocks.org/GoSubRoutine/5b18d019959031f517fc218667faa688
 */

"use strict";

let radio;

function setup() {
  createCanvas(150, 100);
  noLoop();

  radio = createRadio().position(20, 25).changed(redraw);

  radio.option('male', color('cyan'));
  radio.option('female', color('pink')).checked = true;
  radio.option('prefer not to say', color('orange'));

  encloseEachInputLabelPairIntoASubDiv(radio);
  fixRadioDivElement(radio);
}

function draw() {
  background(radio.value());
}

function encloseEachInputLabelPairIntoASubDiv(radioDivElement) {
  const inputs = selectAll('input', radioDivElement),
        labels = selectAll('label', radioDivElement),
        len = inputs.length;

  for (let i = 0; i < len; ++i)
    createDiv().parent(radioDivElement).child(inputs[i]).child(labels[i]);
}

function fixRadioDivElement(radioDivP5Element) {
  radioDivP5Element._getInputChildrenArray = function () {
    return this.elt.getElementsByTagName('input');
  }
}

@jbroux, according to p5::selectAll() method's reference, its optional 2nd parameter can be of 3 diff. datatypes:
https://p5js.org/reference/#p5/selectAll

Parameter container -> String: id, p5.Element, or HTML element to search within (Optional).

On my sketch function encloseEachInputLabelPairIntoASubDiv() is invoked by passing variable radio as its argument:

encloseEachInputLabelPairIntoASubDiv(radio);

And variable radio is of datatype p5.Element btW:

radio = createRadio().position(20, 25).changed(redraw);

B/c p5::createRadio() (and also p5.Element::position() & p5.Element::changed()) returns an instance of p5.Element:
https://p5js.org/reference/#/p5/createRadio

Returns -> p5.Element: pointer to p5.Element holding created node.

Therefore my function encloseEachInputLabelPairIntoASubDiv() is fully compliant to p5js' docs when invoking p5::selectAll() method:

function encloseEachInputLabelPairIntoASubDiv(radioDivElement) {
  const inputs = selectAll('input', radioDivElement),
        labels = selectAll('label', radioDivElement),
        len = inputs.length;

The message "selectAll() was expecting String for parameter #1 (zero-based index), received object instead." shouldn't happen!
B/c that 2nd parameter can be either a String or an object (p5.Element is an object btW).

If you want it, you can let them know about it:
https://github.com/processing/p5.js/issues