Turtlehacks: Draw the Rainbow using Turtle

Turtlehacks: Draw The Rainbow using Turtle

This course has taught me something I had long suspected about how I learn. I’ve realized that I am a lot more comfortable when I am given a problem to solve using code, as in the Chapter exercises, and I am uncomfortable when given creative license to do ‘anything,’ as in the project Turtlehacks. I realized I needed to break down any fun ideas I had into do-able steps so that the liberty of ‘doing something cool’ did not overwhelm or paralyze me. I had the idea to have Tina the Turtle draw pyschedelic designs as the user moved the cursor. So I broke down my project into two steps:

1) have Tina follow cursor 2) have Tina draw a rainbow line

Interestingly, I solved step 2 before I solved step 1, which showed me the value of breaking down a project into multiple, do-able steps so as not to get stuck at the very beginning!

Step 1 was frustrating me. I could find documentation online on how to have Tina move to where the user clicked on the screen, see below:

screen = turtle.Screen()
screen.onscreenclick(tina.goto)

However, I wanted Tina to not only move in straight lines from one point to another, but also be able to draw curved lines. I needed another solution. I found the function ondrag() referenced many times on various forums, and found its proper documentation at Python Software Foundation. (Python Software Foundation seems like an excellent source that I will be returning to again and again. At that link they have the full documentation of the turtle module.) The function ondrag() made it so that the user could drag Tina across the screen, leaving handdrawings. I tried adding the mainloop() function after ondrag() to see what a loop would do. Miraculously, now, Tina follows the cursor even without the user clicking on Tina. I will admit I still don’t fully understand what mainloop() does, or how the sequence of ondrag()and mainloop() causes Tina to follow the cursor, but I will bring these questions to class. I will also admit that there are many artifacts left when the user moves the cursor very quickly. While they are artifacts, I actually think they look quite cool! See code below:

tina.ondrag(tina.goto) #click and drags Tina
tina.mainloop() #when added, Tina follows cursor

For step 2, I wanted Tina to draw a rainbow line. This meant a specific sequence of colors: ROYGBIV. I created a list of the colors in that order, and wanted to loop through that list as long as the program ran. I still don’t know how to create an infinite loop, or if that’s even possible in Python. My solution was the following:

color_list= ['red','orange','yellow','green','blue','indigo','violet']
for i in range(10000):
  for color in color_list:
    tina.color(color)

I iterated through the numbers 0 through 10,000, and for each new number Tina changed colors in the order of ROYGBIV. If I didn’t iterate 10,000 times, Tina would stop changing colors when she ran through the list once. I wanted to include the random module in step 2, so originally I had the following code:

color_list= ['red','orange','yellow','green','blue','indigo','violet']
random.choice(color_list)

However, if I iterated through this, this meant that Tina would draw in random colors from this list, and not in the sequence ROYGBIV, which was my aim. So I chose not to use the random module for step 2.

In the end, I used for loops in my code, and also iterated using the range() function that I learned about in Chapter 4. I wanted to incorportate the random module into my code, but in the end decided not to. I also learned about new turtle functions, including onscreenclick(), ondrag(), and mainloop(). I have yet to write my own functions for turtle, but am excited to do so in the next lesson ‘Functional Turtles’.