E2. Adding Color to Functions

← E1. Color Fill Basics ⏱️ 5 min E3. Multi-Color Bars →

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🎯 Learning Goals

By the end of this lesson, you'll be able to:

• ○ You can add color a parameter to a function
• ○ You can draw color-filled bars with a function

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Review: The Bar Drawing Function

Remember the draw_bar() function you made before?

def draw_bar(t, height, width=40):
    """A function that draws a bar"""
    for _ in range(2):
        t.forward(height)
        t.right(90)
        t.forward(width)
        t.right(90)

Let's add a color featureto this function!

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Step-by-Step: Adding Color

Step 1: Add a parameter

def draw_bar(t, height, color, width=40):
    #                    ^^^^^ Newly added!

💡 Parameter order

• t: the turtle
• height: bar height
• color: bar color (newly added!)
• width: bar width (default 40)

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Step 2: Add the color code inside the function

def draw_bar(t, height, color, width=40):
    t.fillcolor(color)    # 1. Set the color
    t.begin_fill()        # 2. Start filling

    for _ in range(2):
        t.forward(height)
        t.right(90)
        t.forward(width)
        t.right(90)

    t.end_fill()          # 3. Finish filling

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Step 3: Call the function

# Pass the color!
draw_bar(t, 80, "blue")   # Blue bar
draw_bar(t, 60, "red")    # Red bar

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Full Code Example

import turtle

def draw_bar(t, height, color, width=40):
    """A function that draws a color-filled bar"""
    t.fillcolor(color)
    t.begin_fill()

    for _ in range(2):
        t.forward(height)
        t.right(90)
        t.forward(width)
        t.right(90)

    t.end_fill()

# Main code
t = turtle.Turtle()
t.shape("turtle")
t.speed(3)

t.penup()
t.goto(-50, -100)
t.pendown()
t.left(90)

# Draw a blue bar!
draw_bar(t, 80, "blue")

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Code Comparison

Function Without Color vs. Function With Color

No color	With color
def draw_bar(t, height, width=40):	def draw_bar(t, height, color, width=40):
	t.fillcolor(color)
	t.begin_fill()
for _ in range(2):	for _ in range(2):
t.forward(height)	t.forward(height)
t.right(90)	t.right(90)
t.forward(width)	t.forward(width)
t.right(90)	t.right(90)
	t.end_fill()

💡 What was added

1. To the parameters color Add
2. At the start of the function fillcolor(), begin_fill() Add
3. At the end of the function end_fill() Add

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🎯 Mission: Make It Along

Mission 1: Draw a blue bar

Run the code to see the blue bar!

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Mission 2: Change the color and height

draw_bar() Change the color and height in the call!

Example Answer

draw_bar(t, 100, 'red')     # Red bar, height 100
draw_bar(t, 60, 'green')    # Green bar, height 60
draw_bar(t, 120, 'orange')  # Orange bar, height 120

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Mission 3: Complete the function

Fill in the blanks to complete the color function!

Check answers

t.fillcolor(color)
t.begin_fill()
# ... draw the bar ...
t.end_fill()

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🎯 Quiz

Quiz: Calling a Function

draw_bar(t, 100, "red")what kind of bar does it draw?

A) Height 100, blue B) Height 100, red C) Height red, red

Show Answer

Answer: B) Height 100, red

draw_bar(t, height, color)
draw_bar(t,  100,  "red")
#            ↑       ↑
#         height=100  color=red

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Color function practice:

• Add a parameter: def draw_bar(t, height, , width=40):
• Set the color: t.fillcolor( )
• Call a function: draw_bar(t, 80, )

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🧩 Key Takeaways

What you learned in this lesson:

Concept	Description
Add a parameter	def draw_bar(t, height, color):
Use the color	t.fillcolor(color) - Use the parameter!
Function call	draw_bar(t, 80, "blue")

Preview of the Next Lesson

In the next lesson, we'll learn multiple colored barsLet's draw!

colors = ["red", "green", "blue"]
for i in range(3):
    draw_bar(t, heights[i], colors[i])

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← E1. Color Fill Basics ⏱️ 5 min E3. Multi-Color Bars →