5. Combined iteration using zip

The zip function can combine multiple lists so that they can be iterated over together.
See: https://www.w3schools.com/python/ref_func_zip.asp
See: https://realpython.com/python-zip-function/#traversing-lists-in-parallel

5.1. zip 2 lists

The code below uses the zip function to combine 2 lists so that they are like a list of tuples.
The zip object, zip(list1, list2),  is like a list of tuples.
Using list(zip(list1, list2)), the list of tuples below is: [(1, 'a'), (2, 'b'), (3, 'c'), (4, 'd')]
Each tuple has an element from each of the initial lists.
A list of tuples can be iterated over using the syntax: for num, letter in tuple_list:

The code below has 2 lists that are interated over together via the zip function.

from microbit import *

list1 = [1, 2, 3, 4]
list2 = ['a', 'b', 'c', 'd']
for num, letter in zip(list1, list2):
    display.scroll(num, delay=80)
    display.scroll(letter, delay=80)

In the code below, a pitch frequency and an image are combined into a tuple.
This allows a different pitch to be played while each image is displayed.
freqs = range(1760, 880, -128) produces a list like object containing 7 frequencies.
The A-button can be pressed to exit the while-loop using break so that the sounds can be easily stopped.
Pressing the reset button on the back of the microbit will restart the code.

from microbit import *
import music

freqs = range(1760, 880, -128)
animal_images = [
    Image.RABBIT,
    Image.COW,
    Image.DUCK,
    Image.TORTOISE,
    Image.BUTTERFLY,
    Image.GIRAFFE,
    Image.SNAKE,
]
while True:
    for freq, img in zip(freqs, animal_images):
        music.pitch(freq, duration=250)
        display.show(img, delay=250)
    if button_a.is_pressed():
        display.clear()
        break

The code below zips the list of images and the list of frequencies in the A minor scale.
for freq, img in zip(Am_freqs, animal_images) interates over the zipped object, placing each frequency and each Image into the freq and img variables for use.
The A-button can be pressed to exit the while-loop using break so that the sounds can be easily stopped.
Pressing the reset button on the back of the microbit will restart the code.

from microbit import *
import music

animal_images = [
    Image.HAPPY,
    Image.SMILE,
    Image.SAD,
    Image.CONFUSED,
    Image.ANGRY,
    Image.ASLEEP,
    Image.SURPRISED,
    Image.SILLY,
]
Am_freqs = [440, 494, 523, 587, 659, 698, 784, 880]
timing = 400
while True:
    for freq, img in zip(Am_freqs, animal_images):
        display.show(img, delay=timing)
        music.pitch(freq, duration=timing)
    if button_a.is_pressed():
        display.clear()
        break

Exercises

Make a list of 8 arrows and a list of 8 frequencies to play. Write code to show each image as each frequency is played.
Make a list of 12 clock hands and a list of 12 frequencies to play. Write code to show each image as each frequency is played.

5.2. zip 3 lists

The code below requires a breadboard with 3 LEDS.
See: https://pc-microbit-micropython.readthedocs.io/en/latest/breadboards/LEDs_with_resistors.html
The code below zips the list of images, the list of frequencies in the A minor scale as well as a list of pins to use.
for freq, img, pinx in zip(freqs, animal_images, pins) interates over the zipped object, placing each frequency, each Image, and each pin into the freq, img and pins variables for use.
This allows a sound, an image and an LED to be used in the same for-loop.
The A-button can be pressed to exit the while-loop using break so that the actions can be easily stopped.
Pressing the reset button on the back of the microbit will restart the code.

from microbit import *
import music

freqs = [440, 494, 523, 587, 659, 698, 784]
animal_images = [
    Image.RABBIT,
    Image.COW,
    Image.DUCK,
    Image.TORTOISE,
    Image.BUTTERFLY,
    Image.GIRAFFE,
    Image.SNAKE,
]
pins = [pin0, pin1, pin2, pin1, pin0, pin1, pin2]
timing = 400
while True:
    for freq, img, pinx in zip(freqs, animal_images, pins):
        music.pitch(freq, duration=timing)
        display.show(img, delay=timing)
        pinx.write_digital(1)
        sleep(timing)
        pinx.write_digital(0)
    if button_a.is_pressed():
        display.clear()
        break

Exercises

Make a list of images, a list of pitches, and a list of LEDS and iterate over them by using the zip function.