Stacked area chart in Matplotlib - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the correct plotting library for creating a stacked area chart.

Matplotlib

import [1] as plt

Drag options to blanks, or click blank then click option'

Apandas

Bmatplotlib.pyplot

Cseaborn

Dnumpy

Attempts:

3 left

💡 Hint

Common Mistakes

Importing 'numpy' or 'pandas' instead of 'matplotlib.pyplot'.

Using 'seaborn' which is a different plotting library.

We use matplotlib.pyplot to create plots including stacked area charts.

2fill in blank

medium

Complete the code to define the x-axis values for the stacked area chart.

Matplotlib

x = [1](1, 6)

Drag options to blanks, or click blank then click option'

Arange

Bnp.array

Clist

Dpd.Series

Attempts:

3 left

💡 Hint

Common Mistakes

Using list without specifying the sequence.

Using np.array without importing numpy.

The range function creates a sequence of numbers, perfect for x-axis values.

3fill in blank

hard

Fix the error in the code to correctly plot the stacked area chart using plt.stackplot.

Matplotlib

plt.stackplot(x, y1, y2, [1]=labels)
plt.show()

Drag options to blanks, or click blank then click option'

Alabels

Blegend

Ctitle

Dlabel

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'label' instead of 'labels' causes the legend not to show.

Using 'legend' as a parameter causes an error.

The correct keyword argument for naming areas in stackplot is labels but it must be passed as labels=. However, the parameter is labels plural, so the correct answer is labels.

But since the options have 'labels' and 'label', the correct keyword is labels.

4fill in blank

hard

Fill both blanks to create a stacked area chart with a legend and axis labels.

Matplotlib

plt.stackplot(x, y1, y2, [1]=labels)
plt.[2]('X axis')
plt.show()

Drag options to blanks, or click blank then click option'

Alabels

Bxlabel

Cylabel

Dlegend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'label' instead of 'labels' in stackplot.

Using 'ylabel' instead of 'xlabel' for the x-axis label.

Use labels to name the areas in the stackplot, and xlabel to label the x-axis.

5fill in blank

hard

Fill all three blanks to create a stacked area chart with labels, y-axis label, and a legend.

Matplotlib

plt.stackplot(x, y1, y2, [1]=labels)
plt.[2]('Y axis')
plt.[3]()

Drag options to blanks, or click blank then click option'

Alabels

Bylabel

Clegend

Dtitle

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to call legend() to display the legend.

Using 'label' instead of 'labels' in stackplot.

Use labels to name the areas, ylabel to label the y-axis, and legend() to show the legend.

Practice

1. What does a stacked area chart in matplotlib primarily show?

easy

A. How different parts add up to a whole over categories or time

B. Only the total sum of all data points

C. The relationship between two unrelated variables

D. The frequency distribution of a single variable

Solution

1. Step 1: Understand the purpose of stacked area charts

   Stacked area charts display multiple data series stacked on top of each other to show how each part contributes to the total over time or categories.

2. Step 2: Compare options with this purpose

   How different parts add up to a whole over categories or time correctly describes this purpose. Options A, B, and C describe other chart types or incorrect uses.

3. Final Answer:

   How different parts add up to a whole over categories or time -> Option A

4. Quick Check:

   Stacked area chart = parts adding to whole [OK]

Hint: Stacked area charts show parts stacked to form a whole [OK]

Common Mistakes:

• Confusing stacked area chart with line chart
• Thinking it shows only totals, not parts
• Mixing it up with scatter plots

2. Which of the following is the correct way to create a stacked area chart using matplotlib.pyplot?

easy

A. plt.stackplot(x, y1, y2, labels=['A', 'B'])

B. plt.area(x, y1, y2)

C. plt.plot_area(x, y1, y2)

D. plt.stack(x, y1, y2)

Solution

1. Step 1: Recall the correct function name

   The correct function to create stacked area charts in matplotlib is stackplot from matplotlib.pyplot.

2. Step 2: Check the syntax

   plt.stackplot(x, y1, y2, labels=['A', 'B']) uses plt.stackplot(x, y1, y2, labels=['A', 'B']), which is correct. Other options use non-existent functions.

3. Final Answer:

   plt.stackplot(x, y1, y2, labels=['A', 'B']) -> Option A

4. Quick Check:

   Function name is stackplot [OK]

Hint: Use plt.stackplot for stacked area charts [OK]

Common Mistakes:

• Using plt.area which does not exist
• Trying plt.plot_area instead of stackplot
• Forgetting to pass x and multiple y arrays

3. What will be the output of this code snippet?

import matplotlib.pyplot as plt
x = [1, 2, 3]
y1 = [1, 2, 3]
y2 = [2, 1, 2]
plt.stackplot(x, y1, y2, labels=['A', 'B'])
plt.legend()
plt.show()

medium

A. An error because y arrays have different lengths

B. A line chart with two lines labeled 'A' and 'B'

C. A bar chart with two bars for each x value

D. A stacked area chart with two layers labeled 'A' and 'B' over x=1 to 3

Solution

1. Step 1: Analyze the data lengths and function

   Both y1 and y2 have length 3 matching x. The function plt.stackplot creates a stacked area chart.

2. Step 2: Understand the output

   The code plots two stacked areas labeled 'A' and 'B' over x values 1 to 3, then shows a legend.

3. Final Answer:

   A stacked area chart with two layers labeled 'A' and 'B' over x=1 to 3 -> Option D

4. Quick Check:

   Stackplot with matching lengths = stacked area chart [OK]

Hint: Check lengths of x and y arrays match for stackplot [OK]

Common Mistakes:

• Thinking stackplot creates line or bar charts
• Assuming error due to lengths when they match
• Ignoring legend labels

4. Identify the error in this code that tries to plot a stacked area chart:

import matplotlib.pyplot as plt
x = [1, 2, 3]
y1 = [1, 2]
y2 = [2, 1, 2]
plt.stackplot(x, y1, y2)
plt.show()

medium

A. Missing labels argument causes the plot to fail

B. plt.stackplot does not accept multiple y arrays

C. x and y1 have different lengths causing a ValueError

D. plt.show() is missing parentheses

Solution

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

   x has length 3, y1 has length 2, y2 has length 3. Length mismatch causes error.

2. Step 2: Understand stackplot requirements

   All y arrays must have the same length as x. This mismatch causes a ValueError.

3. Final Answer:

   x and y1 have different lengths causing a ValueError -> Option C

4. Quick Check:

   Length mismatch in stackplot = error [OK]

Hint: Ensure all y arrays match x length in stackplot [OK]

Common Mistakes:

• Assuming labels are required to avoid errors
• Thinking stackplot accepts different length arrays
• Forgetting to call plt.show() with parentheses

5. You have monthly sales data for three products over 6 months:

months = [1, 2, 3, 4, 5, 6]
product_a = [5, 7, 8, 6, 7, 9]
product_b = [3, 4, 2, 5, 6, 4]
product_c = [2, 3, 4, 3, 2, 3]

How would you create a stacked area chart showing each product's contribution over time with a legend?

hard

A. plt.plot(months, product_a + product_b + product_c)
plt.legend(['Total'])
plt.show()

B. plt.stackplot(months, product_a, product_b, product_c, labels=['A', 'B', 'C'])
plt.legend()
plt.show()

C. plt.bar(months, product_a, bottom=product_b)
plt.show()

D. plt.stackplot(product_a, product_b, product_c, labels=['A', 'B', 'C'])
plt.legend()
plt.show()

Solution

1. Step 1: Use plt.stackplot with x and multiple y arrays

   Pass months as x and product sales as y arrays with labels for legend.

2. Step 2: Add legend and show plot

   Call plt.legend() to show labels and plt.show() to display the chart.

3. Final Answer:

   plt.stackplot(months, product_a, product_b, product_c, labels=['A', 'B', 'C']) plt.legend() plt.show() -> Option B

4. Quick Check:

   Stackplot with labels + legend = stacked area chart [OK]

Hint: Pass x, multiple y arrays, labels, then call plt.legend() [OK]

Common Mistakes:

• Adding y arrays instead of stacking
• Using bar chart with wrong bottom parameter
• Forgetting to pass x as first argument