Question

How can you display percentage values inside a pie chart in Matplotlib?

• A. Use the autopct="%1.1f%%" argument in plt.pie()
• B. Enable show_labels=True in plt.pie()
• C. Add percentage="on" inside plt.pie()
• D. It is not possible to display percentages inside slices

Hint:

The "1.1f" in "%1.1f%%" formats the number as a float with 1 digit after the decimal point.
To show no decimal digits (e.g. 25% instead of 25.0%), use "%1.0f%%".

Answer 1

The Correct Option is A

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Step 1: Understanding the Question:
The question asks for the correct Matplotlib keyword argument used to calculate and format the percentages shown inside each wedge of a pie chart.

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Step 2: Key Formula or Approach:
In Matplotlib, the plt.pie() function has an argument called autopct (automatic percentage formatting).
This argument accepts a string formatter or a function that calculates and styles the numerical value on the plot.
The format string "%1.1f%%" indicates that the percentage should be displayed as a floating-point number with one decimal place.

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Step 3: Detailed Explanation:
Let us examine the options:
- Option (A) is correct. The argument autopct="%1.1f%%" tells Matplotlib to auto-calculate percentages and print them using string formatting. The double percentage signs %% are used to escape and display a literal '%' symbol on the chart.
- Option (B), show_labels=True, does not exist in plt.pie(). Labels are passed using the labels parameter.
- Option (C), percentage="on", is a non-existent parameter.
- Option (D) is incorrect because Matplotlib fully supports showing percentages inside the slices.
Thus, option (A) is the only valid, correct choice.

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Step 4: Final Answer:
The correct parameter to display percentages is autopct="%1.1f%%", represented by option (A).