What is Matplotlib - Hands-On Activity

What is Matplotlib

📖 Scenario: You want to create simple pictures from data to understand it better. Imagine you have numbers about daily temperatures and want to see them as a line going up and down. This helps you see patterns quickly.

🎯 Goal: Learn how to use Matplotlib to make a simple line chart from a list of numbers.

📋 What You'll Learn

Create a list of numbers representing data

Import Matplotlib's pyplot module

Use pyplot to make a line chart from the data

Show the chart on the screen

💡 Why This Matters

🌍 Real World

People use Matplotlib to see patterns in data like sales, weather, or sports scores.

💼 Career

Data scientists and analysts use Matplotlib to explain data clearly to others.

1

Create a list of numbers

Create a list called temperatures with these exact values: [22, 24, 19, 23, 25, 20, 21].

Matplotlib

# Create the list called temperatures with the given values
# Your code here

Hint

Use square brackets [] to make a list and separate numbers with commas.

2

Import Matplotlib's pyplot

Write the exact line import matplotlib.pyplot as plt to import pyplot from Matplotlib and call it plt.

Matplotlib

temperatures = [22, 24, 19, 23, 25, 20, 21]
# Import matplotlib.pyplot as plt
# Your code here

Hint

Use the exact import statement to access plotting functions easily.

3

Create a line chart from the data

Use plt.plot(temperatures) to create a line chart from the temperatures list.

Matplotlib

temperatures = [22, 24, 19, 23, 25, 20, 21]
import matplotlib.pyplot as plt
# Create a line chart from temperatures
# Your code here

Hint

Use the plot function from plt and pass the list of numbers.

4

Show the chart on the screen

Use plt.show() to display the line chart you created.

Matplotlib

temperatures = [22, 24, 19, 23, 25, 20, 21]
import matplotlib.pyplot as plt
plt.plot(temperatures)
# Show the chart
# Your code here

Hint

Call the show function to open a window with your chart.

Practice

1. What is the main purpose of Matplotlib in data science?

easy

A. To perform complex mathematical calculations

B. To store large amounts of data efficiently

C. To create visual graphs and charts from data

D. To clean and prepare data for analysis

Solution

1. Step 1: Understand Matplotlib's role

   Matplotlib is a tool used to turn data into pictures like graphs and charts.

2. Step 2: Match purpose with options

   Only To create visual graphs and charts from data describes creating visual graphs and charts, which is Matplotlib's main use.

3. Final Answer:

   To create visual graphs and charts from data -> Option C

4. Quick Check:

   Matplotlib = Visual graphs [OK]

Hint: Matplotlib makes pictures from data [OK]

Common Mistakes:

• Confusing Matplotlib with data storage tools
• Thinking Matplotlib cleans data
• Assuming Matplotlib does math calculations

2. Which of the following is the correct way to import Matplotlib's plotting module?

easy

A. import matplotlib.pyplot as plt

B. import matplotlib.plot as plt

C. import matplotlib.graph as plt

D. import matplotlib.chart as plt

Solution

1. Step 1: Recall Matplotlib import syntax

   The standard way to import the plotting module is 'import matplotlib.pyplot as plt'.

2. Step 2: Compare options

   Only import matplotlib.pyplot as plt uses the correct module name 'pyplot' and alias 'plt'. Others use incorrect module names.

3. Final Answer:

   import matplotlib.pyplot as plt -> Option A

4. Quick Check:

   Correct import = import matplotlib.pyplot as plt [OK]

Hint: Remember 'pyplot' and alias 'plt' for plotting [OK]

Common Mistakes:

• Using wrong module names like 'plot' or 'graph'
• Forgetting the alias 'plt'
• Confusing import syntax with other libraries

3. What will the following code display?

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.show()

medium

A. No graph will be shown due to error

B. A bar chart with bars at 1, 2, and 3

C. A scatter plot with points at (4,1), (5,2), and (6,3)

D. A line graph connecting points (1,4), (2,5), and (3,6)

Solution

1. Step 1: Understand plt.plot() usage

   The plt.plot() function draws a line graph connecting points from x and y lists.

2. Step 2: Analyze given points

   Points are (1,4), (2,5), and (3,6), so a line graph connects these points.

3. Final Answer:

   A line graph connecting points (1,4), (2,5), and (3,6) -> Option D

4. Quick Check:

   plt.plot() = line graph [OK]

Hint: plt.plot() draws lines between points [OK]

Common Mistakes:

• Confusing plt.plot() with bar or scatter plots
• Mixing up x and y coordinates
• Expecting no output due to misunderstanding plt.show()

4. Identify the error in this Matplotlib code:

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5])
plt.show()

medium

A. plt.show() is called before plt.plot()

B. The x and y lists have different lengths causing an error

C. Missing import statement for pyplot

D. No error, code runs fine

Solution

1. Step 1: Check lengths of x and y lists

   The x list has 3 elements, y list has 2 elements, which is invalid for plotting.

2. Step 2: Understand Matplotlib requirements

   Matplotlib requires x and y lists to be the same length to plot points correctly.

3. Final Answer:

   The x and y lists have different lengths causing an error -> Option B

4. Quick Check:

   Equal length lists needed [OK]

Hint: Check x and y list lengths match [OK]

Common Mistakes:

• Ignoring list length mismatch
• Thinking plt.show() order matters here
• Assuming import is missing when it is present

5. You want to create a bar chart showing sales for products A, B, and C with values 10, 15, and 7. Which code correctly does this using Matplotlib?

hard

A. import matplotlib.pyplot as plt
products = ['A', 'B', 'C']
sales = [10, 15, 7]
plt.bar(products, sales)
plt.show()

B. import matplotlib.pyplot as plt
plt.plot(['A', 'B', 'C'], [10, 15, 7])
plt.show()

C. import matplotlib.pyplot as plt
plt.scatter(['A', 'B', 'C'], [10, 15, 7])
plt.show()

D. import matplotlib.pyplot as plt
plt.hist([10, 15, 7])
plt.show()

Solution

1. Step 1: Identify bar chart function

   Matplotlib's plt.bar() creates bar charts using categories and values.

2. Step 2: Check code correctness

   import matplotlib.pyplot as plt products = ['A', 'B', 'C'] sales = [10, 15, 7] plt.bar(products, sales) plt.show() uses plt.bar() with product names and sales values, then shows the plot.

3. Final Answer:

   Code using plt.bar() with products and sales lists -> Option A

4. Quick Check:

   Bar chart needs plt.bar() [OK]

Hint: Use plt.bar() for bar charts with categories [OK]

Common Mistakes:

• Using plt.plot() for bar charts
• Using plt.scatter() which makes scatter plots
• Using plt.hist() which makes histograms