2.5: Random

Goals:

By the end of this lesson, I will be able to:

1. Describe how a computer generates random numbers
2. Describe the range of numbers generated by default from a random number generator
3. Explain how to convert random numbers into useable ranges of values in a pogram
4. Explain how random numbers can be valuable in a program
5. Write a program that uses random numbers to impact drone flight

Steps to Success:

1. Random Function
2. Random LED
3. Random Practice Exercises
4. Random Flight Path
5. Number Guessing Program
6. Challenge 1: Magic 8 Ball
7. Challenge 2: Random Flight

The random library in python allows use to generate a variety of random numbers. To learn more about the random library and its functions, click HERE to go to the official documentation. In the following video, we explore how random numbers work in python. Make sure you create a new file in your Level 3 Directory called random_practice before getting started:

One of the ways you can see return values with your CoDrone EDU is through its LED and number randomization. Quick review from the LED lesson: an LED produces color as a combination of red, green, and blue. All of these values range from 0 to 255 corresponding to the color’s intensity, with 255 being the highest. 

For this program, import the CoDrone EDU, time, and random libraries, and then create the drone object and pair to CoDrone EDU. Next, create a for loop that will run three times.

In the loop, create variables that will get a random number between 0 and 255 for red, blue, and green. Those three numbers are combined together to change the LED’s color. For example, if your program returned RGB values of 13, 246, and 197, your CoDrone EDU’s LED would turn aqua.

Next, have your drone take off, wait briefly, and then return the red, green, and blue random numbers with a brightness of 100. This should change the color of your drone’s LED. After that, have the drone land.

Try this program out, and once you see what happens, once you get it working, try to add a random value for brightness as well!

from codrone_edu.drone import *
import time
import random


drone = Drone()
drone.pair()


for i in range(3):

    red = random.randint(0,255)
    blue = random.randint(0,255)
    green = random.randint(0,255)

    drone.takeoff()

    time.sleep(0.05)

    drone.set_drone_LED(red,blue,green, 100)

    drone.land()
drone.close()

To practice our knowledge with the different random functions, try writing programs that do the following:

1. Print a random value between 100 and 1000
2. Select a random color from a list of 5 colors of your choosing
3. Print a random decimal value between 0 and 1
4. Select a random flight sequence from a list of sequences and have the drone fly the sequence
5. Select a random color sequence from a list of sequences and have the drone play it
6. CHALLENGE: Print a random value between 10 and 20 WITHOUT using the randint(a,b) function

Now try to create a program that selects a random integer for a move() function and a random integer for a flight direction function (pitch, yaw, roll, or throttle). Have the drone take off and fly the direction and duration based on the two random values you generated.

For this activity, we are going to create a list of flight directions AND random numbers and see where our drone goes! To do this, create a new file in your Level 3 directory called random_flight. Now import CoDrone EDU and random, create your drone and pair it.

We are now going to create 3 variables. One is a list of flight directions, the others are the power and duration for that movement:

directions = ["yaw", "pitch", "roll", "throttle"] #different flight path options
duration = random.randint(1,5) # 1 to 3 seconds for our movement
power = random.randint(20,100) # Random power value that starts at 20 so we at least see some movement

Now that we have these created, let’s make our movement based off of the random values:

drone.takeoff()
rand_dir = random.choice(directions)
if rand_dir == "yaw":
    drone.set_yaw(power)
elif rand_dir == "pitch":
    drone.set_pitch(power)
elif rand_dir == "pitch":
    drone.set_roll(power)
elif rand_dir == "throttle":
    drone.set_throttle(power)

Finally, add the move and land commands:

drone.move(duration)

drone.land()

Try out the program and see how it works! Once you have it running, can you think of any other additions or optimizations you could make to the code?

You know that game that starts with “I’m thinking of a number…” and you have to guess which number the person is thinking of? You’re going to play that with your drone!

After importing libraries (CoDrone, direction, time, and random), creating the drone object, and pairing, have your drone take off. Next, create a variable called  throttle and set its value to 20.

Create a variable called  number that will store and return a number between 1 and 10. Next, create a while loop. Create a variable called  guess that will prompt the user to input a number between 1 and 10, and will then store that value. Within the while loop, set up conditionals. If their guess is too low, the drone should throttle down. If their guess is too high, the drone should throttle up. If their guess is just right, the drone should do a flip. The program should also include a print statement for when the user guesses a number that is not between 1-10 and a break if they want to quit the program. Finally, the drone should land.

Your final program should look something like this:

from codrone_edu.drone import *
import time
import random


drone = Drone()

drone.pair()

drone.takeoff()

throttle = 20

number = random.randint(1, 10)  # randomly choose a number between 1-10

while True:

    guess = int(input("Guess a number from 1 - 10... or enter 0 to quit: "))  # get input from user

    if guess == 0:
        break

    elif guess > 10 or guess < 0:
        print("Number is not between 1-10. Try again.")

    elif guess == number:
        print("Perfect!")
        drone.flip("front")
        break

    elif guess < number:
        print("Too low!")
        drone.set_throttle(-throttle)
        drone.move(1)

    elif guess > number:
        print("Too High!")
        drone.set_throttle(throttle)
        drone.move(1)

drone.land()
drone.close()

For this challenge, you will have your CoDrone EDU create random noises using the buzzer. To complete this challenge, do the following:

1. Choose the random notes that your drone will choose from and place them in a void function that has one parameter, iterations.
2. Inside the the function, the iterations parameter will be used to determine how many times the notes will repeat in a loop.
3. For each loop iteration, generate a random note and duration and have the CoDrone EDU produce that sound.

Once you have completed this program, your drone should produce random sounds that repeat several times depending on your input.

In this lesson, you learned about the random Python library and how it works! You learned how the library can be used to generate random numbers and how those values can be used in a program.